I liked iv. There where some annoying things, but MS live stuff was no reason not to play, you could get rid of that stuff very easily. I still play in a sandbox way every now and again, there are some great mods for the PC too.
I am also surprised they are releasing 5 so soon, which would imply they are using the same engine, which would be a first for a GTA sequel.
What about the "V" logo on that splash/temp page? Looks kind of retro..like 50s maybe?