While I really liked the potential for m1_google_analytics, we ended up using mono_ga because I could get it to work. The version of m1_google_analytics I tried was trying to use the old code and Analytics wouldn't recognize it as installed on the site. I was disappointed by that because it had the potential of tracking file downloads, something that mono_ga doesn't do. (Jeff S seemed to think that they performed a neat trick to get that to work, but I'll let him comment on it if he wants.)
Still took some configuration to get things working, but once I had it set, all was good. I think the worst problem I had is that if I put the config values in the wrong place in the template, I got a completely blank site when I loaded it. I get some pretty good information from it now - enough to do what we need, anyway. Just would love to get the file tracking working as well. If you have any success with the m1 extension, please report back on how you got it to work and what version of TYPO3 you're running.