I am a full-time work-from-home WAN geek. I have Sprint data service, with an old PCMCIA card in a D-Link DIR-450 router; it's my backup Internet connection. From time to time, I've used it in short intervals (1 week) as my primary connection. I used to have problems with the connection resetting every 6 to 18 hours or so, although the connection state has seemed much more stable in the last few months. It still won't hold an outbound VPN connection for a full day at a time; my sessions last anywhere from 4 to 20 hours before needing to be restarted (and the same connection over DSL lasts for weeks). Throughput is more than servicable, and the rate is more constant than I'd expected. Jitter can be higher than you'd want for VoIP, especially if there's any other traffic on the line. The jitter could be mitigated if I used a decent router, but I still think I'd see a performance gap between wireless and wireline delay consistency.
For mid-speed service and 99% uptime, it's a perfectly viable alternative. It's especially useful in some rural areas where the cellular data network reaches farther out in the country than DSL or cable. If you need great service 99.9%+ of the time with low latency and minimal jitter, stick with wireline.
