It is actually a pretty good service. It provides FTTH service, which opens the door to a lot more bandwidth than coax. The Internet service is significantly better than Comcast, here, and only slightly more expensive. The television service is marginally more reliable, and provides a lot of foreign language channels that Comcast doesn't have room for. The telephone service is okay; not quite as good as Comcast.
Of course, after your promotional rate expires, it's a bit more expensive, but it is worth the extra money.
A lot of the reason FiOS is great on the TV side is not so much because it is fiber to the home, but because it is a new network and doesn't have any analog channels to waste bandwidth. Early on, Verizon took the decision to completely get rid of all of its analog channels which freed up a lot of bandwidth for HD channels. Cable companies still have analog because it's difficult to get rid of it without losing subscribers and also because of FCC mandates.