I had a Dyson V8 for six years. The battery finally gave up around the same time the trigger started sticking, and faced with the replacement cost — battery, trigger, plus the new model is somehow $750 now — I decided to try whatever the best non-Dyson cordless was. The Shark PowerDetect kept coming up, so I bought it. After three months I do not miss the Dyson.
The dust-detection light is the gimmick that turns out not to be a gimmick. A green LED in the floorhead shines forward across the carpet or hardwood, and any dust or hair you hit lights up like a forensic scene. The first time I ran it across what I thought was a clean floor I was visibly chastened. After two or three runs you stop seeing dust at all, which is the part the marketing leaves out — it works, and it makes you confront how often you were calling "done" too early.
Suction is where the comparison to Dyson matters. The PowerDetect is not as raw-powerful as a V15 Detect on its highest setting, and if you have deep wool carpet that hasn't been cleaned in months you'll notice. For day-to-day hardwood, low-pile carpet, and pet hair, the difference is invisible. The auto mode senses surface type and dust level and adjusts power, which sounds like a brochure feature and actually works — it runs quieter than a Dyson at the same task and seems to use less battery doing it.
The battery is the structural advantage. It's removable, swappable, and Shark sells spares for around $80, which is less than a third of what Dyson charges for the equivalent. Run time is around 60 minutes on the eco setting and closer to 15 on max. For a normal apartment-sized clean, one battery is enough. For a house, you keep a second one charging.
Where the price shows is the materials. The plastic on the PowerDetect feels lighter and hollower than the Dyson's. The dust bin latch is fine but doesn't have the satisfying clack of the Dyson trigger; the brush roll is easier to remove for cleaning, but the housing flexes more than I'd like when you press down on a stubborn spot. None of this affects how it vacuums. It does affect how it feels in your hand, and if you've owned a Dyson you'll notice.
The attachments are a mixed bag. The crevice tool and the upholstery brush are useful. The "pet multi-tool" is the kind of attachment that lives in a drawer forever — it works fine but is bulky enough that I'd rather use the crevice tool with a manual swipe. Storage is a real problem; without a wall mount you have a stick vacuum that wants to lean against something, and the box doesn't include a mount. I bought a generic one for $20.
Verdict: Buy this if you want most of the Dyson experience at noticeably less than Dyson money, and you don't mind the lighter feel in the hand.