Too many of the reviews of the Steam Controller have come from the perspective of limited first impressions geared towards plug and play. Only a portion of the tech-focused sites have really dug into it, and found out what it can really do.
The Steam Controller right now out of the box with default control templates isn't very good, as usually the haptic pad sensitivity is bad, and the gyro assistance isn't even on.
If you get used to the pad, bother to either tweak or try community templates, the thing can easily beat out an analog stick for aiming. Then add in the dual-stage triggers, back paddles, and just the crazy amount of inputs you can bind to the pads...you end up with games where you don't EVER have to lift your thumbs off to hit anything.
Only thing is that it doesn't measure up to the precision of a good mouse, but it's the closest a pad has ever come, and also natively acts as a mouse for games that don't read xinput commands in main menus for some PC games.