The only semi-interesting thing would be cheap international calls - but I have Skype for this already.
Voice mail, I don't use. If it was improved like with GV - I'd still not use it. SMS, I have plenty of free texts, never exceed my limit - though I wonder how they get away with making them free, given that carriers make lots of money with that.
One number to rule them all - that would be cool - except if it's controlled by one company which will eventually seek to monetize. Those chefs and massage services cost money... I don't, by the way, see how being available on the phone to anyone at any time, no matter what number they call and no matter where I am - as a feature. More like a bug. I am already easily reachable on my phone, via SMS, via emails. I don't need to be any more available.
Anything that I'm missing? Why would I want GV?