I don't get all the hate people are throwing at the controller for *adding* a thumbstick. The left pad is still there, I played games with it, movement sorely needed a thumbstick, period.
The left pad can be used for platformers but the input doesn't feel as good as a stick to me. For fighting games you NEED a stick, the pad would definitely not cut it by any stretch, it's not easy enough to use because unlike a dpad you don't have raised buttons so clicking on it like it's a d-pad, while it works, is harder because there's no raised surface telling you where the right/left/up/down is. The tactile feedback isn't there which at least personally, throws if off for me.
The two back triggers are digital inputs not analog, which I hope they will later change. Analog triggers let you do a lot of cool things we simply can't do with Mouse and Keyboard and it's one of the few things missing from the platform that I feel could be added now.
Regarding the use of the pad as a Mouse and Keyboard replacement (which is the intent): It does the job well. I have gone and made changed in the Steambox OS when mine broke with one of their updates early on and the wi-fi drivers got nuked and I never once plugged in a mouse to do it. As far as games are concerned it works pretty well, but requires a bit of training for your hands since you need to get used to how the pad itself works (acceleration, different mouse speeds depending on the ring you're on).
Having used the controller a few times already my wish list is this:
1) Customizable sensitivity/mouse acceleration outside of games
2) Analog triggers
3) Pipe dream: ability to swap in/out a thumbstick on the right side for people who like twin stick controls for shooters and action games.
That's pretty much all I feel is missing now.