I'm on the 4G Monthly $50/mo plan. First 100mb at 4G speeds then throttled to unlimited 2G speed. It doesn't bother me surprisingly. I mostly use web and apps for Facebook, Twitter, etc. I don't watch YouTube on my phone because I never really cared to. Prefer my laptop for that. Unlimited talk and text. I'm happy.
They also offer the 4G Monthly $70/mo plan for unlimited talk, text and 2GB data @ 4G speeds. Better for those for heavy web users and YouTubers. Even the $70/mo plan is cheaper than my $115/mo unlimited everything plan with Verizon. I will NEVER sign another contract again!