Wirefly is a good honest site. The only issue is the fact you actually sign 2 contracts. 1 for Verizon and 1 for Wirefly. If you break Wirefly's contract you owe them $300+ and they charge your credit card. Breath of contract would be changing your plan or ending service within 6 months. After your first 6 months are up you are no longer under Wirefly's seperate contract.
If you are careful and know you can keep youre Verizon service for at least 6 months and choose the correct plan for your wants and needs from the get go you will be fine.