We received the vacuum about 2 weeks ago now and was amazing taking even out of the box even. So futuristic and cool not having to worry about a cord any more that my wife has to wrap up or worry about tripping over. Awesome vacuum BUT.....its a little odd but when the vacuum turns up the power you hear a click in the head like it sucked something up that keeps making it click. I have looked at it, taken it apart to make sure I didn't forget something but its annoying when you are using it and you hear it ticking in the head of the vacuum and you think its something stuck in the roller. Maybe its just me being picky but when you spend that kind of money on a vacuum you don't think it would make ticking sounds. Other than that, very cool vacuum, cleans well and the light show it does for when its dirty and clean, it actually works. The stuff it picks up is amazing. We still love it but the ticking will be something you have to get used to I guess is all.

I have given this unit 30 days....I hate that I wasted so much money on my two Dyson stick vacuums, first time I ever bought anything on sale that I would have gladly given full price for, battery last way longer than I do, sensing system is so cool, it does what it need on its own to get the job done, first vacuum i have ever owned that will keep up with my three Aussies

The skimpy directions page is not and never will be enough and figuring how to use this vacuum without an owner’s manual is far from intuitive. A manual that Shark should provide with the vacuum, not expect me to search for and read online or print out at my expense. For the lack of a manual I would’ve given it a one star but because the vacuum seems to work well, once I finallyfound the information I needed, I’ll give it a 3 stars. And what’s the stupidity of sending the vacuum empty bin in the quiet mode? Who vacuums and then needs the bin not to empty for fear of waking someone up? That kept me from vacuuming for a couple of days when the vacuum filled up and I couldn’t get it to automatically empty or find a way to empty the actual vacuum container. And I have better things to do than constantly search YouTube and the internet.

I have two complaints about this vacuum -- the first is that it doesn't work smoothly on some of my carpets. It becomes impossible to push in certain directions making it useless as a vacuum for those. Second -- the tiny foam& felt filters get clogged immediately. They don't even get through my whole house before they are completely caked and dirt/dust is all the way through. I have the clean and empty base and that filter is also caked through and I can't find replacements for it. This machine is not cheap, so having two major problems like this is not acceptable.

I had previously only used the Dyson line of vacuums. However after repeated issues because of difficulty cleaning with their filter systems, I ordered the PowerDetect Clean and Empty vacuum. I am SO impressed with the power of this vacuum. It is the most expensive Shark Cordless vacuum cleaner. The ease of cleaning (overall) the vacuum and how well it vacuums is EXCELLENT. And not even close to the costs of the Dyson. Have had it 3 months so I have tested well..: a true Shark fan now

I totally like the detection of what surface it is vacuuming, how light it is, and how easy it is to maneuver. The battery lasts a surprisingly long time—or maybe I don't last that long! The hand tools are not the greatest, but they are suitable for a quick flyover on the trim boards. The self-clean system does not fully empty the contents; it sometimes gets hung up on the way it is designed. I liked it so much that I bought another one!

I bought my shark BU 3521 about 2 1/2 - 3 months ago and it was the best! I loved it, I never had a stick vacuum before. The handle with the battery broke off so it’s unusable now and I don’t have the box or receipt so I can’t get a refund. I think the handle with the battery attached to it without any reinforcement is too much strain.

I bought the cordless PowerDetect just a few weeks ago. I do like the concept of no cord but unfortunately the battery does not last long enough to vacuum my home. So I still need to vacuum with my corded vacuum too. I sure wish that Shark would include the second battery - which would certainly be helpful in keeping my floors clean. I like the clean/empty feature too. I empty it after each use even though you dont have to.

For the price of the vacuum, I’d expect it to work on shag area rugs and it sadly does not. It’s just okay on any other surface. I am not impressed and will most likely be returning. I have a 8 yr old Navigator Lift Away that works amazing but it’s clunky and I have to keep plugging it in each room and deal with the cord which is why I bought this but I’d still need my old vacuum with this one. Not worth it.

I just bought this vacuum yesterday and I'm not overly impressed with it for what i paid, i have a very small house and couldnt finish my house on one vacuum session, my battery only last 15 minutes on boost mode. This vacuum would be great if it had a better battery life, but I am very disappointed in how much I paid for such little battery life.