I've been printing out our boarding passes at home ever since NWA first offered the service. Only had a problem one time - the boarding pass didn't print out all the little bar codes. Just went to the agent at the airport and had another one printed for me. No trouble at all. They've improved the system since they first started, too. Now you can get a reprint if the first attempt fails. The "home printed" passes work just fine at the gate. Never any problems there.
We really like this service when all we have is carry on luggage. Then it really saves us lots of time. It doesn't always save you time, though. That's especially true if you have luggge to check. If we have luggage to check, we like to use the curbside option. A tip is expected, but we don't mind that. All of my luggage comments are for the MSP airport. They may not apply to your regional airport.
I like the self-check in option. It's nice to get the extra FF miles, but I really do it because the system lets you change your seat assignments. Several times, I've gotten what I consider better seats doing this. Of course, you can only move to vacant seats and you can't assign yourself to exit row seats or to the seats reserved for the elite FF members (unless you are one). NWA lets you "check in" via your home computer 24 hours ahead of time, though, so you can get first crack at the available seats if you able to check in at that time. It also gives you some idea of how full the plane is.
If I can answer any specific question, let me know. Be glad to help.