Bought a Steam Controller, and here are some first impressions.
As you might know, originally the Steam Controller was designed to be more like this prototype:
The final retail version, however, is a bit different (probably having gone through dozens of different iterations, based on actual testing):
I always felt that this arrangement, however, is quite awkward. In the prototype the ABXY buttons are not in the traditional formation, but they are very close to the touchpads, making them easy to reach. In this arrangement, however, they are quite far from the right touchpad. Especially the most important button, ie. the A button, is relatively speaking really far. (Of course you can map the buttons however you like, but it still feels awkward.)
The idea of the touchpads being the main mode of control was kind of thrown out of the window and defeated by the addition of the thumbstick. (You can still, of course, configure the controller to have the left touchpad act as a thumbstick, but given that you have an actual thumbstick, probably nobody is going to do that.)
There is nothing inherently wrong in that (ie. having a thumbstick.) There is a problem in its positioning, though. The controller still seems to consider the touchpads to be the main modes of control, while the thumbstick is relegated to a secondary role, a bit awkardly positioned. (It's even more awkwardly positioned than in the PS4 controller, which has a similar positioning for the left thumbstick.)
Given that people (and most games by default) are going to use the thumbstick for movement anyway, why not put it in the natural position? Likewise I think that the ABXY buttons should have been put into their natural position, rather than awkwardly shoved where they are now.
In other words, I really think that the different controls should have been arranged like this:
As it is in the actual controller, it feels awkward to use the right touchpad and the ABXY buttons. As well as the left thumbstick.