Developing Apps

So here's the thing. For years I've enjoyed tinkering with PHP and MySQL as a hobbyist. I built my own website from the ground up and now and again I make little web apps for fun. For the last year or so, though, I've been trying to improve my knowledge of more advanced (relatively speaking) code. I use some programming knowledge in my day job, and feel it would be nice to expand on what I already know.

At the moment, I'm really tempted by developing for Windows Phone 8. C# seems like the most accessible out of the three key languages for app development (the others of course being Objective-C [which is out of the question anyway as I'm not a mac person] and Java). I spent yesterday reading through the language specification and started to get a feel for how it works. As someone who knows PHP it seems like a jump, but not too much of a leap.

I also think it might be a nice (potentially the best ever) time to get into Windows Phone development, given the open market, fleet of new phones and the limited-time-only developer annual registration fee of $8 instead of $99. For someone who's looking to learn a bit on the side and play around with software, it seems like a nice option. Hell, one day I might even come up with an app a handful of people like.

I just wanted to see what people's thoughts on this kind of thing were. Are there any other amateur developers out there who have something to say about choosing C# over the alternatives? Am I being overly optimistic about Windows Phone 8? Will it turn out to be a damp squib?

One note: I noticed that the Windows Phone 8 SDK is ONLY available to Windows 8 users. Well, I can upgrade for a negligible fee, but I would be very, very sad to leave Windows 7 because it is such a nonsense-free OS. Windows 8, from what people are telling me, is slick but has a few limitations / quirks that take a while to get used to. So I guess I'm also asking if you think it's worth shifting my whole OS to a new version just because I want to play around with code now and again...