I switched from Verizon to Sprint in July 2011 for the HTC Arrive, so I'm not a recent convert but this does give me better insight on the experience. I had no problems until the end of the year when Sprint started selling the iPhone. It seems like everyone in my area bought one, because the network quickly became unusable, especially near the university. Sprint's network was by far the worst network in the area from the end of 2011 through earlier this year. With NV upgrades in my area, things improved. The improvement was enough that I upgraded to the HTC One when it came out instead of waiting a few more months for my contract to end.
The 3G is still not as fast as Verizon, despite our area being mostly NV upgrade complete. Neither is the 4G. However, the data actually works now. This is a big improvement from where it was, and rarely are the speeds too slow to stream music / browse the internet. Watching videos is tricky over 3G, but on 4G it's no problem. The only other issue with Sprint is that their coverage is not nearly that of Verizon's. If you are going to be in civilization most of the time this won't be an issue, but if you venture outside the city you will quickly notice the downside of 1900MHz plus fewer towers. If you are in an area where Sprint has no service, you will roam on Verizon (typically 1X and voice only, it's "unlimited" but if you use excessive roaming Sprint may boot you). Oh, and the handoff between Sprint and Verizon towers is rarely smooth - expect dropped calls if you are moving in and out of roaming coverage.
Even with the slightly over 1 year where my phone was useless except for phone calls, I'd say it was worth it for unlimited data. Houston is seeing a lot of NV upgrade activity, so I don't think you'll have a problem.