I just installed the Windows 7 Phone SDK and all is component parts, which was a long but easy chore. Well, the first time it hung forever and I had to remove a bunch of components before it would install correctly.
The process of getting a simple phone app built and running on the emulator was about like I expected. I already learned basic XAML programming, and I found nothing extraordinary about the Phone classes (so far).
However-- (big pause) The level of support for real network programming on the WP7 is abysmal. First, you can only use the WCF "service" model, which currently only runs over HTTP. In other words, you must have a server hosting a WCF service or no go. The claim (see this forum among many others) is that resource-poor Microsoft didn't have time to test sockets correctly before releasing this still-wet-behind-the-ears new product. Maybe so.
On the other hand, maybe their urgent desire to establish Azure as the cloud platform of choice had something to do with this. If you can't do your own networking you're forced to rely on hosted faciliies, either web servers or cloud communications. Either way, Microsoft gets more money from you.
Since HTTP runs over TCP and HTTP is supported in its web browser, I sense something altogether fishy in Microsoft's limitations for this first version of the WP7. Why couldn't they simply allow synchronous (blocking) communications over single TCP sockets, which is probably what the built-in web browser is doing? Reason-- because they want to kill peer-to-peer.
What really (really) concerns me as a civil libertarian is that this coincides with ongoing, onerous attacks against peer-to-peer operations from both government and big business. I sense that there are deep, powerful forces at work that want to work with ISPs to "white-list" the internet and kill peer-to-peer operations. The crippled version of the WPF7 may just another example of a product brought to market too soon. Or it could be part of a larger, decentralized effort to kill arbitrary point-to-point internet connections. Government wants to monitor everything, and PTP is messy to monitor. Businesses assume everyone doing PTP is an IP pirate and want to block it all. Now, arguably the biggest product launch of the year for a smartphone fails to include the most basic communications capability for the internet. Accident? Hmmmm.
Suffice it to say that without sockets or multitasking, this product is more a toy than a platform. On the iPhone, most people run their applications an average of twice. Microsoft seems to be depending on games and social networking sites to drive WPF7 sales. They will probably fail.