Long ago bumped myself up to hard. Not really struggling, seems about right for me, although I'm only in the last 20 days. I'm not really in serious mode, either. Looking forward to testing ironman mode on expert -- for some reason I've always gotta play permadeath in the highest difficulty even if I get caned. Oh, I've been watching those Let's Plays by Das and he seems to be cruising normal, although he is a very strategical player. Casual/Normal definitely don't seem too hard.
I noticed that same thing when watching his stuff; I get the impression that he was expecting Normal to be harder. Where right now it seems very easy, with most things just going squish in one easy hit and the player not taking much damage to their already high-ish shields. I know I'm not really the best one to judge that particular difficulty level, but still. Considering that alot of players will start on Normal, I keep wondering if the low challenge of that is going to give the wrong impression?
As for these exponent things, I have to wonder if the changes with those are going to make hard/expert easier? Not that I'm any good with math stuffs.