It takes some getting used to, sure, but I'm to the point now where I use it for all sorts of games comfortably, ranging from Civ V to Rocket League to Mass Effect. I'd put it about on par with mouse+kb depending on the game, and I definitely prefer it to a standard Xbox or Playstation controller. The only thing that I wish it could do is work with consoles, but I understand why that would be too difficult to do. I miss my grips and touchpads when I have to use other gamepads though... :/
UPDATE: After a few months of usage the right bumper busted and I am currently in the process of getting a replacement. Unless Valve really messes up the replacement process I still totally recommend the controller though.
Some helpful info:
OS: Windows 10 & Arch Linux. (check the wiki if you're having issues with legacy games)
Games that I've played that have native support: Portal 2 Screencheat The Talos Principle
Some games I've played using legacy support: Just Cause 3 (Did some long-distance shots with this one, some of the top on the leaderboard last I checked...) Mass Effect ARK: Survival Evolved Civilization V Battlefront II DICE's Battlefront (Requires messing with Origin, ugh...) Rocket League Fallout 3 Borderlands 2 Spec Ops: The Line Minecraft The Stanley Parable