Pros: Verizon has, in my experience, the best coverage in the Northeast. Customer service has generally been good, although at times one gets conflicting information from different customer service staff.
Cons: There are some dropped calls in known problem areas. In the Boston area, there are predictable problems on Route 2, in Brookline, in the Tip O'Neill tunnel, etc. Verizon costs are a little higher than some competing carriers. Also, there are still large areas of Maine, NH and VT with no coverage.
Summary: In general, Verizon seems to have the best coverage in the Northeast, with generally good customer service. Prices are a little higher than other plans, but the in-network option is good (especially with such a large customer base in the Northeast). Had Sprint before, which wasn't a bad service, but had more holes in their coverage than Verizon.