ooma for years now and I think I had maybe issues twice (and i killed a unit once, but that was my fault). I have the Premier and love it. I have it synced with my Google Voice, so when I travel I have 1 number where people can call me (and with google's calling rules, I don't get a 3am telemarketing call due to the time difference).
I do have Obi as a backup and when I used it (while waiting for my ooma replacement), I had no issues. Obi worked great.