The T720.....along with a whole lot of other Motorola phones were really extremely bad. Lousy build quality, less than great UI, sub-par reception, and a really bad screen. However, I've been using a v300 for a bit over a month now (which, for me, is a pretty long time, I go through phones very quickly......I'm a malcontent when it comes to phones, what can I say ). The reception is absolutely amazing, easily one of the best I've used. I say this in comparison to pretty much any other GSM phone that will work in the US. The UI is excellent (not to mention pleasing to the eyes. Nice transparency effects all over the place), the build quality is quite good (only complaint being that there is some SLIGHT movement of the top half of the flip, nowhere near as bad as the V60 series, but it is there), and the screen is absoluetely gorgeous (excellent color reproduction, and a very high resolution, 176x220).
The highest compliment I can give it is that I'm actually keeping it for the forseeable future, and the only reason I'll be getting rid of it is to get its big brother the v600 (basically the same phone, biggest difference being the v600 has bluetooth).
So, yeah, in short, I highly reccomend this phone to anyone considering t-mobile