The V6 is an ok car. it makes jsut shy of 200hp, which isn't bad, but it's not the same as the 265hp GT, either. If you don't really care to go fast, you'll probably have fun with the V6. The problem with mustangs is that once you have one, you start hanging out with Mustang people, and they start to rub off on you, and then you want it to go fast, so then you sell the V6 and buy a V8. I've seen it happen more than once.
As it is right now, I'd rather buy a used GT than a new V6, but that's my preference.