MS- Closing a few studios with amazing talent. Not purchasing Bizarre. Really misusing Rare. People may actually buy a Kinect Viva Pinata game done well now, but nobody was going to get into that series so early in the lifecycle of Halo Box 2. Just their general use of Rare was bad, although I really liked almost all of the games they worked on. RRoD goes without saying. No telling where Lionhead is headed. Losing Bungie was pretty big, but I think it was at least handled well, and a studio of comparable talent was created to replace them. Canceling 1 vs. 100 and not continuing with advertised based competitive free gaming with Joy Ride and Full House Poker.
Sony- Bad management of some major franchises. SoCom, Ratchet, and Killzone come to mind. Meanwhile their new franchises while typically very good outside of Uncharted (which is great) had some success but were not really blockbusters. Resistance, LBP, Infamouse, Mod Nation, MAG, Heavy Rain. Then you had the big early bombs such as Haze, Lair, and Heavenly Sword. Of course their biggest mistake was probably taking 3rd parties for granted when it came to MS. The original XBOX would get about half the third party games, while 360 pretty much got all of them with about one or two major exceptions and then created a larger worldwide audience for those franchises. Not to mention they got the better version the majority of the time and exclusive content either early or permanently for games. Which brings me to the difficulty 3rd parties seem to have had programming on the system. Of course they screwed up on pricing, and then downgrading the system quickly to make it more affordable. Also very slow to catch up with XBL even with their service being free. Oh and the month where nobody could game online right after the launch of ... Well lets not rub that wound any further.
I will update this as things come to me or as I read the thread:
Rockstar: GTA4 was a great game but it had its head stuck up its ass. If you want to go serious or darker with the series, then you cannot still have every single bit of advertising in the city refering to cocks, fucking, drugs.... The mixture of satire and realisim only works when the two meet up at some point. If you are going serious then just put up a Coke sign instead of a Cock sign. The game lacked the humour and over the top gameplay of some of its predesesors, yet the whole atmosphere of the city was a 12 year olds joke. Now we have Max Payne 3. I have not played it yet so it is hard to bitch. But for me it looks like they have the essence of the combat down, in a world that does not at all remind me of what I found interesting about the first two games. It looks like Max Payne got dropped into random GTA locations. On this issue, I am not experienced enough to comment further.
Nintendo- I do not really want to get into it. For me as a Nintendo fan, they did the opposite of what I wanted this generation, but they were widely successful with that model. The main mistake is the power of the system itself. That is why they are having the shortest generation of the big 3, but with those crazy sales they are still so far ahead that nobody would call the Wii a mistake. I just hate the damn thing. And I could dig into mistakes and such, but they made so much damn money. And the next iteration does not look much better for my gaming needs.