Well I joined Helio December 8th and I love the service. They use Sprint towers so the coverage is great. I own the Ocean and I looove it.
Its the best mobile device I have ever owned. I was going to go with TMO and get the SKLX but the Ocean does so much more and its a little bit cheaper than the SK. I purchased my phone from a Helio kiosk in a mall and I got mine for like $150. Also, they have All-In Plans which are fabulous. I have the All-In 500 plan($65/mo) which includes unl nite and wknd mins, mobile2mobile, unl web, unl text and pix, IM, Becon Buddy, Google Maps, You Tube, HelioUp etc. The only downside is that they don't currently have an automated system yet so when you want to check your mins you will have to login to your account online or call customer service. I actually called customer service last night to find out when they will have an automated system the the rep told me that they are working on that but she doesn't have a date on when it will be up and running. Anyway, the customer is great and they do have a 30 day happiness guarantee. You can try it out and if you don't like just return everything within the 30 day trial period.