Sarah Thomson, Vice President – Business Development at IUGO took a stab at comparing the 4 platforms from a gaming company’s perspective. Looks like WP7 did very well indeed 
Battleground Game Space
WP7 rates only second to iOS and with a high score of 7/10 (iOS is at 8). The things working for WP7 are that the OS has been a dream to work with for developers and Microsoft’s focus on gaming as a very important part of their offering. The convergence of gaming with Xbox Live is also seen as a big plus.
Heres what Sarah had to say about the other platforms
iOS – “Apple got a lot of things right; a platform that was a pleasure to develop on, gorgeous hardware, an intuitive OS, processing power, a well-established distribution platform, seamless payment process…Yes, there are challenges too: discoverability is a bitch, Apple is a wall of silence, rules and guidelines have been sketchy at best, hypocrisy ran amuck with app approvals…“
Android – “fragmentation wasn’t just about handsets though, as handset makers and carriers can customise and utilise whichever version of the OS they want. Then there’s the refund policy.Another big error was that the Android Marketplace launched with free content, so everyone expected everything to be always free.“
BlackBerry – “IUGO has released three titles on BlackBerry, and they’ve pretty much done nothing..BlackBerry has an app storefront, but the majority of sales occur on carriers’ storefronts..the biggest problem with BlackBerry is that the handsets are designed for business use not gaming.“
WP7 is seen as treading the middle ground between Apple’s restrictions and Android’s freebies!
Via pocketgamer