I have one, and for $30 it's great. I was in the same boat, just couldn't afford another more expensive wheel. I have a G25 attached to a Playseat that I use for iRacing and rFactor, but it's hooked up to my computer at my office. But more than the cost, I like having a very small, wireless footprint for the TV room where the PS3 is. Once you get the hang of the wheel paddles, it's no big deal, and I don't have any problem at all going between a G25 with pedals/shifter and the all-in-one wireless. In all honesty, GT5 isn't "sim" enough to worry about it.
It stays fairly stable on your lap, and the "pontoons" have slots in them, so if it slides around too much for your liking, you can put a nylon or similar strap though it and wrap it under your legs to really lock it down. I don't find that necessary, but a friend of mine with the same wheel does that.