Some random thoughts
1. Instagram is not on Windows Phone. Fact.
There's no first party app but it exists in third party form (Instance, 6tagram, etc). First party support becomes a big deal if they screw with the API's (which Instagram has done once) but otherwise it's the same as iOS when everyone used Tweetie and Tweetbot because there was no official Twitter client.
2. Google isn't developing apps for Windows Phone right now outside of a collab effort on YouTube with Microsoft. Fact.
Google services are never gonna make it to WP unless it gains significant marketshare or MS kills Bing. The companies hate each other. Even on the collaborated YouTube app, Google screwed over MS by blocking it anyway. Reasons were fabricated - Google denied MS metadata and then blocked the app on account of not providing an experience that required that metadata. And they also blocked the app because it wasn't coded in HTML5, even though neither the iOS and Android YouTube apps are coded in HTML5. Both companies are basically screwing with each other right now because MS encroached into search.
Luckily I have Metrotube so I don't have to wait for both companies to make peace (which is not gonna happen anytime soon if at all). So yeah if you're an avid Google Services user, I'd agree that's a good enough reason to not use WP8.
3. Android App store and iOS App Store blows away the MS App Store. Fact.
The app gap is WP8's biggest obstacle, that's undeniable. At the same time the ecosystem has been growing. The biggest catalyst for WP app growth isn't MS, but Nokia, because they're pushing essential WP8 apps (Path, Flipboard, etc) as Nokia exclusives. As long as Nokia's vested, I expect the ecosystem to become good enough, with the exception of Google Services integration.
5. Microsoft Windows Phone is 3rd Place in the Market. Fact.
They're in a distant third, at the same time there's a reason they swapped spots with RIM - they're doing something right. Historically the smartphone market has always had room for at least 3 players. Back in the day you had Symbian, Windows Mobile, Palm OS and BB OS competing. Even if you're not a fan of WP, the 3 party competition is good for the market and pushing the bleeding edge of tech and getting it into our hands.
The Nokia WP8 handsets have the best cameras in the industry and Android OEM's and Apple are gonna feel pressure to push for feature parity. Android OEM's have already began - they're incorporating Xenon flashes, Samsung is throwing anything at the wall to see what sticks, Sony is releasing the Honami which has a good chance at having the best integrated camera behind the 1020 and 808. This kind of competition is good. Otherwise all you get are incumbents doing next to nothing - like Apple right now, reskinning iOS 7 and calling it a day.