I just made the switch to FiOS... I'm pretty happy with it.
So far, it's been like dealing with a totally different company when dealing with anything related to FiOS. They show none of their old nickel-and-diming that they did on the normal phone service, and they have been very responsive.
Not only that, when they got to my house, we didn't have a fiber drop to the house (it was at the end of the block), so the tech called his boss, who sent a truck full of people to dig the trench and run the line the rest of the way to the house (across several neighbors' yards). When they were done they cleaned it all up so well you wouldn't even know they had been there.
The combined install time for Cable and Fiber was about 6 hours I think, but I wasn't there for the whole thing.