Pros: Coverage is outstanding due to using Verizon and Sprint cell towers. Customer service is amazing (read summary). Phones are great.
Cons: Price (read summary).
Summary: Customer service:
I have had service with Helio for 10 months. Initially I switched because the phones were really nice. Shortly after the switch I acquired a girlfriend who was on AT&T, formerly Cingular. She lives across the country and my phone bills were outrageous due to talk time. I was paying $175/mo for 4000 minutes just to keep up with our calls! I recently decided I was going to switch services because I couldn't afford the bill. I've been online for the past 4 day's searching for the best deals and for the best celluar provider. The decision came between AT&T and T-Mobile. AT&T because I would get free mobile-to-mobile with my girlfriend, and T-Mobile for their Fav 5 plan. As I was looking online for my account number to port my number to another service, I noticed that Helio offered a new plan. $119 unlimited anytime, including unlimited nights and weekends. This also includes unlimited text, and Internet. I called Helio after I saw this and spoke to an English speaking customer service rep within 2 minutes after calling. I told him my issues and he informed me that the $119 plan was a promotion for new members, but since they wanted my business they would offer it to me anyway.
The customer service has been outstanding every time I've called. They've taken money off bills when I've gone over, they've changed my plans to accomadate my usage without extending my contract, and always treated me with respect.
I've been with all major carriers except Verizon. AT&T had terrible customer service and mediocre reception. T-Mobile had decent customer service but mediocre reception. Sprint had terrible customer service, medium pricing, but pretty good reception/coverage. I have never used Verizon, however my friends who have verizon have no complaints and they seem to have the best reviews.
Since Helio uses Sprint and Verizon towers, the coverage is outstanding! I've used mine all over the country including Virgina, Key West, FL, Arizona, California, and driving across country. I've never had coverage problems.
One more thing... If you compare other carriers plans with all the benefits which Helio includes, you'll find it's almost the same price.
For the coverage and customer service you cannot beat Helio. These days it's nearly impossible to speak to someone on the phone who's nice, let alone speaks English. I would gladly pay the extra $15/mo for outstanding service.
Hope this helped!