Yesterday, I Ordered a myTouch 3G. Still trying to check out the reviews. As soon as I receive it, I will update you with my review.
T-Mobile My Touch 3G Android phone touchscreen is made by HTC and running on the Android operating system, Their products are used in Verizon and At & t phones as well. Over all HTC products have been pretty reliable in the past.
check out this site for a bit detailed review on myTouch 3G.
U
Usman Aleem 
This phone is awesome! We did a review of it that you can read here: http://www.magnatecha.com/2009/09/review-t-mobiles-mytouch-3g.html