It appears from the pictures, that the device has solid build quality. The keyboard looks like it will be a pleasure to use as well.
While the front of the smartphone is no different than the original myTouch 4G, save for the sliding keyboard, the back of the device is now a home for an 8 megapixel camera unit (1080p video recording is very likely to be available) with auto focus - a serious upgrade from the 5MP snapper of the original.
We already know that the T-Mobile myTouch 4G Slide will ship with Android Gingerbread, dressed in a slightly modified version of HTC's latest Sense 3.0. Reportedly, the device is seriously fast but there is no conclusive information on its CPU (it might be a 1.2GHz, dual-core as in the HTC Sensation).
Now that we have the rumor circle which started with the leak of HTC Doubleshot back in April near its end, there is little left to do, but wait for an official announcement from T-Mobile and HTC. As always, we will keep you posted so stay tuned.