By aspect — in detail
Isolation
Moderate · 7 srcThe headline strength and the point of widest agreement: reviewers across editorial, measurement and enthusiast outlets rate the active noise cancellation best- or near-best-in-class. The wrinkles are a faint electronics hiss some hear in silence, a design choice that ANC can't be fully turned off (only an Aware mode), and one critic who rates it roughly level with Sony rather than ahead.
“the noise-canceling could well be the best out right now”
CNET (David Carnoy)
“the QuietComfort 45 headphones offer the best active noise cancellation we've tested”
PCMag (Tim Gideon)
Measured
SoundGuys' bench found deep attenuation — it estimates airplane engine hum will "sound one-eighth as loud" — and ASR measured strong reduction in the low frequencies. The caveat both ASR and PCMag flag is a faint white-noise hiss with NC on; a vocal minority on Reddit find that hiss (and the fact ANC can't be switched fully off) hard to live with, and Newsweek rates overall ANC roughly a toss-up with Sony's WH-1000XM4.
Comfort
Strong consensus · 7 srcThe other pillar of agreement, and essentially uncontested: light, plush and easy for long sessions, repeatedly singled out as among the most comfortable over-ears in the class. The only recurring caveats are pleather pads that warm the ears in heat and a fit that isn't secure enough for workouts.
“The QC45 is arguably the most comfortable pair of over-ear headphones out there”
CNET (David Carnoy)
“The fit is exceptionally comfortable, with plush earpads and an equally cushioned headband.”
PCMag (Tim Gideon)
Measured
Weighed around 240 g (238 g on CNET's scale) — light for a wireless over-ear — with gentle clamp. The consistent caveats: the synthetic-leather pads "steam your ears up pretty good in warmer environments" (CNET), even ASR noted they "did heat up my head pretty quickly," and the fit is too loose for running.
Broad agreement on the shape, not the verdict: listening reviews consistently describe an upfront, bright, energetic voicing tilted toward the treble rather than a neutral one. Whether that's a strength or a flaw is exactly where sources split (see bass and treble). The twist is that the most technical measurement puts the ANC-on curve close to the research target — so the perceived brightness is partly rig- and preference-dependent.
“predictably energetic, brawny sound”
WIRED (Simon Lucas)
“The sound on the QuietComfort 45 tends toward the sparkle of the higher frequencies more than other comparable headphones.”
Newsweek (Tyler Hayes)
Measured
With ANC on, ASR's bench reports "compliance with the target is very good especially in bass" and that "our relative frequency response looks really good" (with the unit off it's "not that hi-fi"). PCMag frames the stock tuning as "massaged enough that we wouldn’t call it flat response." SoundGuys' own rig instead reads an overemphasized high end — a genuine measurement-vs-measurement disagreement, detailed under treble.
Genuinely split. One camp — including the most measurement-minded reviewer — hears a rich, full, well-controlled low end that never turns boomy; the other finds it decent in isolation but thin and lacking depth next to similarly priced rivals like Sony's XM series.
Measured
ASR measures the ANC-on bass as on-target and "superb"; What Hi-Fi hears it as tidy rather than bloated ("It never suffers from bloatedness through a grippy bassline"). The dissent is comparative — Newsweek and some owners find it lacks the weight and depth of the Sony XM4/XM5.
Where it splits
Rich, full and well-controlled — a strength, especially with ANC on.67%
“Turning the headphone on brings a revelation with superb bass and excellent overall response.”
Audio Science Review (amirm)
Decent in isolation, but shallow and disappointing next to rivals.33%
“in direct comparison with similarly priced headphones, the bass is disappointing here”
Newsweek (Tyler Hayes)
Quietly well-regarded where it's discussed: vocals and instruments come through present and clear, and the tuning is especially kind to speech and podcasts. The recurring caveat is that on busy, bright tracks the elevated top end can push vocals back in the mix.
“a spacious and communicative midrange”
WIRED (Simon Lucas)
“This does a good job of making speech intelligible”
SoundGuys (Christian Thomas)
Measured
SoundGuys notes the bright tilt means on some busy tracks "the vocals and drums take a backseat to the cymbals," and PCMag heard "perhaps a bit of added sibilance" on vocals — the midrange itself sounds clean, but the treble emphasis can crowd it.
The most polarizing axis. One camp hears the top end as crisp, bright and present without turning harsh; the other hears it as over-emphasized and grating on busy, cymbal-heavy material — enough that some reach for EQ. Unusually, the two measurement outlets disagree about what the treble is even doing.
Measured
SoundGuys' rig reads the high end as overemphasized versus its preference curve ("Anything with lots of cymbal shimmer will be a bit grating") and recommends a treble cut. ASR's rig instead measures a dip at 7-10 kHz and calls the overall curve near-reference.
⚠ vs. listeners — Two measurement-driven outlets reach opposite readings of the same treble region — SoundGuys measures an over-emphasis, ASR measures a dip — which is a large part of why listeners split so sharply on whether the top end is lively or grating.
Where it splits
Crisp and bright without turning harsh — part of the fun.42%
“The higher-register brass, strings, and vocals retain their bright, prominent presence”
PCMag (Tim Gideon)
Over-emphasized and grating on bright tracks — wants a treble cut.58%
“an overemphasized high-end relative to our preference curve in its out-of-the-box tuning”
SoundGuys (Christian Thomas)
The consistent shortfall for the reviewers who care about it. Mainstream outlets find the sound clean enough and don't dwell on resolution, but the more audiophile-focused critics single out detail, subtlety and dynamics as where the QC45 clearly trails class leaders — and even PCMag grants the tuning isn't accurate for true audiophiles.
“They're not the most subtle or revealing pair of headphones around, really”
WIRED (Simon Lucas)
“we become aware of a shortfall concerning timing”
What Hi-Fi?
Measured
This is a technical-ceiling critique, not a measured defect: What Hi-Fi finds it "Beaten for dynamics and timing" by rivals, while CNET, testing casually, heard only "just a touch better clarity" than the QC35 II — a difference in how much resolution each reviewer was chasing.
Soundstage
Thin evidence · 1 srcLightly covered. The reviewer who addresses it directly finds the QC45 organizes space competently and gives instruments room to breathe; separately, some note rivals like the Sony sound a touch more open. Too thin a base for a firm verdict.
“they organise a soundstage pretty well, give every element of a recording a bit of breathing space”
WIRED (Simon Lucas)
A mild split between in-hand feel and longevity. The construction feels good and even a touch premium to some reviewers, and the move to USB-C is welcome — but it's unmistakably light plastic, and owner reports flag reliability over time (units that stop turning on, Bluetooth drops, pads wearing) as the real weak point rather than the initial feel.
“The 45 has excellent feel and the white color gives it a feeling of luxury.”
Audio Science Review (amirm)
“Bose has apparently reinforced the headband with glass-filled nylon”
What Hi-Fi?
Measured
SoundGuys scores Durability/Build Quality 6.9 out of 10 — below the same review's Comfort (9.2) and Battery (9.4) scores. Amazon's new-unit listing averages 4.6/5, but reliability, battery and connectivity are the recurring low points in owner reviews, and long-term Reddit owners describe earpads wearing out in about a year.
Contested and heavily price-dependent. At the $329 launch price, critics call it outclassed — even by Bose's own 700 — and not a value buy; more favorable reviewers and long-term owners still call it a fair package for the ANC-plus-comfort combo. Nearly everyone agrees it's a much easier recommendation once discounted, which it very often is.
Measured
SoundGuys notes it's "an easier buy" once discounted (it cites finding it around $279), and long-term owners on Reddit echo that it's a fair buy at that lower price. What Hi-Fi's blunter take: "Sonically, your money can buy better."
Where it splits
Not worth it at the $329 list price — rivals and Bose's own 700 do more.53%
“at its original price is not worth the money”
SoundGuys (Christian Thomas)
A fair buy for the comfort-and-ANC package, especially on sale.47%
“certainly lives up to the price tag”
PCMag (Tim Gideon)