I tried to do a Google search on this new phone and came up rather empty. What I do know is that the G1 is rather dated. It is a 2.0 plan phone and only can achieve 3G cell data speeds. While the new 5W I will assume is a 3.0 plan only phone, most likely it is a GSM phone and you will be tossed onto another carrier ( T-Mobile ) while your old G1 is a CDMA phone and is on the Sprint network. The 5W most likely is a 4G LTE phone as well. I’m going to take a guess but if I recall the G1 only had 1GB of RAM, I am going for 2GB of RAM on the 5W because of the price. More RAM is just better.
These are all guesses I have about the 5W, but for the year it is and the price they are asking, I’m sure it is a better budget phone than the old G1.