They function smoothly but sometimes get stuck after adjusting the weight. If they were $50 less expensive, they would've beat out a year of gym membership.
Pros: Comfortable, Easy Storage, Easy To Set Up, Easy To Use, Quiet
The moment the gym closed, I was online to order these. Don't remember how I knew about them - maybe saw an ad in Men's Health. Anyway, I didn't want to make room for a set of dozens of dumbbells. The Bowflex 552s are the answer to that. Though they can be a bit "touchy" - if the plates shift at all in the holder, the dumbbell can lock up - I love them. I can be a bit touchy, too, so...
Easy to adjust, but found myself having to troubleshoot the weights many times when they were fixed in place. Dial is typically easy to maneuver. Love that I can increase the weight in small increments, how functional the eights are, and how easy it is to store them.