Yeah it says Overall: Very Positive (4,690 reviews), yet, when you scroll down it you'll see that there are Positive (8,281) Negative (2,088) reviews. Not sure how the Steam review filter works. Those numbers aren't exactly stellar with how much Valve tried to shill the controller along with the Steam box. They were hoping that everyone was going to buy it. I nearly did, but after trying it, nahh.
Sometimes 30 minutes is enough to test an RPG. There are games that are just shit and shallow and what you see is what you get. A game like Arcania, for example. It's so shallow and the game expreience doesn't evolve beyond what you are shown in the first 30 minute tutorial. I was stupid enough to play it longer but I don't feel like it validates my opinion over someone else if they came to the same conclusion as me within 15 minutes of playing the game.
But I digress, a game is not a controller. Playing with a controller is not the same as trying to decode the mechanics of a deep RPG or strategy game. If a controller doesn't sit well and the input feels off right off the bat, then it's not good. You'll get used to it after a while, but that doesn't mean that it's good. With human adaptability we can get used to virtually anything. A good controller feels like an extension of your hands and not something you need to
The controller is so different than anythihng else before it that that 30 minutes is just not enough time to test it and even begin to figure out its workings. There are many things that don't give a great first impression, RPGs, movies, music, whatever. Yet with more time spent you start to unlock their genius and could end up really liking them after awhile. The Steam Controller is no exception. The Xbox 360 controller or Dualshock 4 look like rocks with sticks on them in comparison (not only design-wise but functionality-wise as well.)
To put it simply, if a reviewer spent 30 minutes with an RPG, a controller, a console, whatever, that would not be a very thorough review. Hell, at 30 minutes with the Steam Controller I was completely lost. It wasn't until spending several hours using it as well as programming it and learning what it could do before I was converted.
And converted I am. The thing is a marvel of technology. Years ahead of everything else. It is sort of like the Shield tablet that I've discussed before. Technology that is so out of left field and new that people are confused by it and dismiss it. I know, I did the same thing at first. But then upon using it, a silly grin comes to your face as you say, "Oh, THAT is why this thing is awesome!" Happened with the Shield and now with the Steam Controller for me.