I have one but don't "love" it, I voted that anyways since you gave no other option. It's a great concept but has flaws.
#1, biggest issue for me. Its built for midgets. AKA people under 6' tall I am guessing. All I know is that I am not "tall" (6' 2") but the steps are not positioned right at all for comfortable work. I can never stretch my legs, my knees are always bent and its a bit uncomfortable to work for a long time. When you really get cranking on stuff you can't use your entire body for leverage because you slip off (i'm scrawny, I depend on the rest of my body for muscle). Cutting the steps off and positioning them where they are comfortable fixes these issues. I really am curious what height person these were made for.
#2, the stupid step welded to the bottom for when you have it extended all the way. Cut that thing off. After you trip on it how many times you too will get pissed and cut it off. It sticks out further than everything else so you are always tripping on it.
#3, the wheels lock but it doesn't stay in place very well. Nature of the beast though, not much you can do. Kind of like and engine stand, they never stay in place either.
#4 The legs stick up very high and this can limit what you can get under all the time. Not often, but every once and awhile its an issue. Simply making them heavier with smaller material would've been nicer.
#5 the pad *****. I'm a very skinny guy and after you lay on that pad for 5 minutes it feels like a board. Do your self a favor when you get it and ditch the crappy foam right away for some denser foam. Thicker if you want.
The little pouch on the front is pretty useless, take it off if you want. Just get a tool stand that you can place where ever needed to hold your tools.
It may just be me, but whenever I get off of the thing and back onto my feet my sternum will hurt for a minute or so and just overall feel a bit weird. Could be partially to do with the step placement being less than ideal for my size combined with the poor pad.
It's been awhile since I've actually had to use mine, I've got a port in right now and laying on it with that much force isn't too comfortable. I think I might just make my own in the meantime based off the original but tailored to my size and with some improvements. Since I basically want to change the entire thing I figure its better than hacking the old one up since I can just sell that.
A couple other ideas I had for it were to mount an LED worklight underneath it to shine where you are working, and maybe a slide out tray for tools. a better adjustment system wouldn't hurt but the one on there works. I honestly haven't found a use for the tilt system though.
It would really be neat if there was a way to rest your feet in the air more when you are really reaching for stuff, you'll end up dangling them in the air a lot when reaching for the backs of engine compartments, especially stuff thats low. Your calves will be sore.
Overall though, the concept of a topside creeper is genius, the above is just my opinion. Its a great tool but may need some custom tailoring to meet your needs.