I had the phone a day before the official launch. 3G in Philadelphia was already up and running and I went through the prerequisites of changing and modifying my plan, then reverting it, then changing it again because I was being a spoiled brat and wanted it just right!

The phone looks awesome in person (It's not photogenic at all) and the included earbuds and USB cable were more upscale and useful then my last HTC phone (T-Mobile SDA). The phone feels good in the hand and the keyboard is nice, but my big fingers have issues with some of the keys. The trackball is a nice addition and useful and NOT a waste, I find myself using it instead of finger scrolling while surfing the web.
Web browsing is good on the 3G network, with fast page downloads. Unfortunately I cannot connect to my router using Wi-Fi, but was able to use a free hot spot in South Philadelphia and the speeds were better and had no initial problems. The GPS is not spot on all the time but it works well and I see myself using it again and again. Also Google Maps render quickly and looks good on the screen.
I downloaded some of the applications from the marketplace and overall they are good but nothing super major, such as support for stereo bluetooth or a flash player built for a better web browsing experience, and document support. If someone can make a video capture program DO IT SO I CAN LOVE YOU FOREVER!

Also the library of applications are not as vast as Apple's but the phone has not been out for a month and I tell myself to give it time and let it flourish.
The OS looks good and is simple to use, no flash and pizazz, just a intuitive OS. I can gripe about the lack of pizazz but then its good, just not...pizazzy. I wish it had a built in task manager like Windows but you can download somewhat similar programs from the marketplace.
Taking photos is a real disappointment with this phone. I do see that is has auto-focus but you have to be VERY STILL to get a good shot. The photos pail against my last phone (Nokia XpressMusic) and that has a 1.3MP camera! Again if that can be fixed via a program MAKE ONE SO I CAN LOVE YOU FOREVER!!!

My biggest gripe is the battery life. With 3G on, GPS off, and using the web browser or IM applications my battery hitting midway fairly quickly. Music playback alone is not all that bad but its still shorter then my last phone (Nokia XpressMusic 5300). I love the speed of the 3G which is why its always on. I don't feel confident being out and about all day (8am-8pm) and using this phone for music, web and IM without having to charge it at least once. I had a Zune and will pick one up again soon. I am always listening to music indoors and outside around and about.
My overall experience has been positive but there are glaring flaws that I hope can be addressed in future updates of this phone. I knew what I was getting into (I did a LOT of online research) and I am not disappointed too much. I will recommend to future and current T-Mobile customers to pick up, as this is the best phone (In my eyes) they have available.