I just got the unit. It was easy to put the wheels on and it feels very stable.
After putting the wheels on, I put the creeper on the floor and sat on it. It didn't try to flip up on me. It didn't try to scoot out from underneath me. It stayed put and made me feel very secure.
After sitting, I laid down and moved around a bit and everything worked well. The wheels swiveled nicely letting me just glide around on the floor. Very nice.
Then I got up. Sitting up was easy and again when on the edge and getting ready to stand up, it didn't scoot or try to flip or anything. Made it very easy to get up from.
Initially impressions has me very happy with the purchase. Hoping it continues to work this way for years to come.