Supposedly, there's a rule of thumb that says that dead reckoning by integrating readings with a MEMS sensor is about as good as walking around with your eyes closed. I didn't even get mine working that well when I tried, but I'm sure it's possible if you get the pre-integration noise filtering right.

Lately I've seen a lot of app notes and open-source code written by/for amateur drone guidance developers, which I suspect would have helped me a lot.