The problem here is going to be that Sprint's network is almost always congest. So you can expect to be constantly deprioritized on this plan. This is why I left Sprint in the first place (after being a customer for almost 15 years).
I signed up for it, as I had an unused phone, a Vonage VOIP number, and Vonage was up to $25/mo. Got in the last day before they canceled. Yes, they add taxes and surcharges. Bill is actually 20.55 with automatic billpay. I hooked the Sprint phone up to a $13 bluetooth interface to my existing cordless phones, and it works like a charm. Saving $5 a month, and have a backup in case the internet goes out. Testing with Speedtest, shows right at about 2.2 Mb/s.