TL;DR: If controllers are to games what instruments are to music, then most other controllers are like a fretted guitar while the Steam Controller is like a fretless Violin. Yes it is more difficult to use at first, but it is still possible to "play in tune" and once you've gained mastery over it you can do things on it that simply cannot be done on other controllers. Moving on.

"I want an innovative controller that caters to the needs of pc gamers and has plenty of powerful customization options that allow for a versatility befitting the pc gaming platform".

*gets a steam controller*

"ICK! Why isnt it the same as my xbox controller?!" - most negative reviews.

It does take getting used to if you are coming from more traditional console controllers (xbox/playstation controllers), as it lacks a "legit dpad" and a right analog stick, and does have a different physical layout that focuses on the touch pads over the other input methods. However, it is not limited by what it lacks but rather the person using it.

It more than makes up for not having traditional inputs by not only emulating those things - and surprisingly well once you get over the learning curve - but also doing so much more as the touch pads and the software that makes them work - Steam Input - puts it into a class of input devices all on its own. Heck, despite the pc mustard race's npc-like "mouse good, controller bad!" bible thumping, a skilled Steam Controller user can even go toe to toe with kbm users in competitive games and hold their own just fine!

For everyone not willing to put in the effort for any number of reasons (the "plug and play" crowd having the most legit reason imo), yeah the Steam Controller is gonna suck. You get out of it what you put into it.

But for those willing to learn it, it is sublime. And a damn shame its been discontinued.