Generally, but it has some issues. I found the C-stick to be very uncomfortable with the lack of a cap, and you can't really press two face buttons at the same time unless one of them is A. The latter isn't usually a problem, but certain games, like the Arkham series, would be virtually unplayable. That there's only one shoulder button on one side is also pretty weird. The dual stage triggers are pretty neat, though, and the only other controller I've used with them is the Steam Controller, which has a pretty steep learning curve.
Yeah, figuring how to roll my fingers among the face buttons to do fancy stuff in Metroid Prime was tricky. I also like to use my thumbs to reach across the controller to the dpad and c stick on the opposite side so that I can change visors while on the move, for example.
I can't play souls games on anything but a steam controller. The pads are so much better than a stick for camera movement, and the pads are incredibly useful with the games' awkward layout for sprinting.
Currently playing Armored Core 6 with a Steam Controller, and I love it. But... the right track pad leaves a lot to be desired.
The best aspect of the Steam Controller, without a doubt, is the modularity and shareability of it. The standard control scheme a game tries to assume, most of the time it stinks. But being able to browse through community-made control schemes and finding one that works for me is fantastic. The highest downloaded control scheme for AC6 got me 95% of the way there; I just had to change the bindings of the back pedals to suit me. Now it uses the track pad and the gyro in conjunction-- track pad for big sweeping movements and gyro for small adjustments-- and I love it.
The C-stick and Z bumper are the two big weaknesses. If it had a proper twin-stick design instead of the C-stick nub, and actual bumpers that felt good, it would hands down be the best controller ever designed.