I'll stick to business weaknesses, since it's more objective
In Nintendo's case, i think they've got the problem of not doing enough investment in growing their own software base, either in terms of getting aggressive about bringing high-quality 3rd party exclusives on board, or just in creating more first-party studios. This more than anything else is what holds them back. The DS has been drifting on older games for a while now, so clearly they need more. They've also been too conservative about hardware production, probably missed out on 10 million sales they could have made sooner than they did, or more.
Microsoft also needs to invest in more first-party development. In their more immediate contest with Sony, the difference is made up by the fact that the fewer big brands that Microsoft has are much stronger than Sony's first-party brands, for now, but Microsoft is relying too much on momentum right now (that people buy 360 games because they have bought 360 games in the past, and also because other people are buying 360 games. This isn't a strategy that you can sustain in a console transition at all, just ask Sony or Nintendo). Equally, they're really going to need to twist some devs' arms about Natal if they want Natal to get anywhere.
Sony needs to figure out exactly why people buy handheld game consoles, and also needs to figure out immediately that the digital-only model is not the future at all. They also have this fixation on prestige games which is really non-helpful in terms of selling consoles. As great as Team ICO's games are, how much money are they investing into that that they could be pouring into something that's going to sell consoles? Killzone 2, Uncharted 2, Gran Turismo 5, are all great games, but i think they could have been made far more economical than they were. Sony's propensity to push the envelope is "good" for the industry because it sets a higher standard, but what exactly has Sony gotten out of breaking the bank?
Monster Hunter: pissing me off since 2010.
