A lot of old publications refer to Uaru amphiacanthoides as the poor man's discus. I think it has a lot to do with the compressed bodies, large bright eyes, and the fact that they feed their fry off skin secretions to an extent (not as crucial as discus).
They are great fish but grow very large and will eat everything. You'll need a big tank, good filtration, and stay on top of your water changes. Like discus, they are sensitive to water quality.
Mine didn't grow much once they hit 6" -- I think I slowed them down a bit by putting them with my severums which out-compete them for food (which is a surprise, considering how voracious a uaru's appetite is). I think if you have the tank size for it, go for it. $10 - 15 for a large juvie is a great price. I never even see good quality uaru here.
I agree about discus being pretty easy... they're no different than any other cichlid. Pay attention to the few basic requirements (frequent water changes, high quality food, warm water) and they will thrive, as long as you start with healthy stock. The main problem with discus is that most LFS and online dealers sell culls and low-grade fish. You really need to get them from a reputable breeder or importer to ensure that they've not been put through hell by the LFS. If you start with sick/weak/stressed stock, chances are they're going to crash on you.