PC gaming is good at a variety of things:
* Indie games are much easier to launch on PC. No dev kit, no running things by MS or Sony, and no 50mb size cap. Just release over the Internet, or on Steam, and Bob's your uncle.
* Steam, Gamer's Gate, etc. provide developers with lower cost-of-entry points for publishing, and higher percentages of the profits than official publishers do.
* Publishers should like it because they don't have to pay MS or Sony the typical gratuities.
* I'd say used game sales are as great a problem for consoles as piracy is for PCs.
* Nobody needs a top-of-the-line computer for gaming anymore. The most taxing game in recent memory is probably Metro 2033, and it runs just fine (medium settings, but it looks great!) on my 2-year-old middle-of-the-road laptop.
* MMOs and social gaming obviously have no competition from consoles. The price of entry is "having a PC," generally speaking, and pretty much any old computer will work.
* RTS, TBS, pretty much any strategy game and most deeper RPGs, are at a serious disadvantage on consoles.
* Modding is pretty much available only on PC.
* It's possible to play modern games for only $400 nowadays. A bargain-bin PC and a last-generation graphics card, and you're set. And with games mostly stagnated at the graphical level of the last hardware generation, you'll be able to keep playing pretty much anything you want for years!
* Based on recent sales figures, PCs are responsible for more than half the total reported revenue (with digital distribution notoriously difficult to count). The remainder is divided between consoles and mobile platforms, and the console section is divided between Sony, MS, and Nintendo.
* The price of entry for the consumer is much lower on the software front. A new game will cost you $60 on consoles; aside from arrogant publishers like Activision and Ubisoft, most new games on PC cost at most $50, and "niche" titles generally start at $40 and go down from there. And then there's Steam sales - a huge backlog of games from recent years, available for a pittance, all in one place!
* Niche experiences are much more readily available. Gamer's Gate has "euro" games that you can't get anywhere else (White Gold: War in Paradise, to name one), Good Old Games has various classic titles from years far past, Minecraft and Dwarf Fortress and similar are all available online, and Paradox churns out strategy game after esoteric RPG after strategy game.
So, really, the only people who are really at a disadvantage on PC are the triple-A game publishers making FPS after FPS, and not noticing the surging tides of RTSs, RPGs, and other more complex genres emerging on the PC. (Paradox Interactive is largely responsible for this)
The last couple of years (2008-09), it's seemed like PC gaming was suffering - but 2010 was good for us, and going into 2011, it looks like PC gaming is swelling mightily. We're not dying - we're not even infirm. We're seeing a record-breaking surge of new life!