Sooo, now that I've played through to my first few levels, I feel I can probably comment on what I've found to be painful on the first impressions.
To establish, I run kb+mouse combo; I steer the Cogmind with the keyboard for precisions sake, and use the odd shortcut as it's convinient (especially grab and aquire!), but tend to run the rest of the menus, firing weapons, and identifying objects and robots via mouse. I have to say, it's worked extremely well so far. That said, I'm finding a couple extra mouse-clicks more than strictly needed.
As a newbie, the right-click button is mighty handy for learning what each robot is and (even more important) what the heck each part does. Using it, however, has tripped up a few bits of polish:
1) When you click on a line item to learn what it means, you can't then click away until you've clicked the text box itself. 'clicking away' is pretty common in UI language, so its absence can be mildly aggrivating.
2) The right click menu is just as guilty - you need to click that again to make things clear as well. Especially frustrating when what you really wanted to do was right-click one robot to see what it was, then right-click another robot in quick succession... like, say, when a patrol shows up and you're working out what each robot is all about. It'd be ideal if you could keep right-clicking stuff and have the sidebar just refocus on the new item as you go; likewise it'd be nice if clicking/moving 'elsewhere' simply closed the information panel.
Is there a reason to leave it up until explicitly click-to-close? As far as I can tell, I can't actually do anything until I've closed it again, but this could be a rookie mistake.
3) (I figure the very first level is safe from spoiler alerts, but anyhoo: spoiler alert!) The first level has you chat to a friendly NPC, then wander through until you find propulsion - your first opportunity to learn how attaching stuff works. Obviously you want to attach stuff, right? ... yeah, actually putting on those legs or wheels and activating them will slow you down. While I get the idea for it (It'll be to your benefit soon enough once you start grabbing other junk), and I also get why the naked cogmind should be speedy if weight-vulnerable... the combination is somewhat tricky to actually implement.
4) Do mining claws let you dig through dirt? Mining lasers do, as I determined via experimentation, but I may have missed a line in their descriptor that explicitly identifies the two items as being excellent at dirtbusting? If there isn't, should there be?