Setup was fast and easy. First, I connected the OBi to home Ethernet network and plugged in a phone. Next, I completed the online registration process and entered my Google id and password. I made my first call within 5 minutes of opening the box. However, I immediately noticed some voice quality issues so I connected the OBi directly to my router instead a bridge - that fixed the issue. In the month I've been using it full time (I'm on conference calls for most of the day) I've only had one problem. When I tried to make a call recently I got a message "there is no service available." I followed the online help, logged on to the admin portal and everything looked fine. I decided to unplug the OBi to reset it and that fixed the problem. I haven't experienced the problem since.
I called Charter Cable to cancel VoIP service and they offered me a special deal to keep my service but at a lower price than cancelling it (a no brainer). I have 25Mb/s broadband service through Charter as well but I regularly see speeds in excess of 40, 50 and sometimes 60 Mb/s (see below). I use DirectTV for satelite TV. While I intend to continue to use the OBi and Google Voice as my primary phone, it's nice to know I have a backup with Charter in addition to Sametime Unified Telephony and my AT&T cell phone leveraging a microcell.
Update 3 April 2012: In the past week I've experienced significant call quality issues and dropped calls. I have switched back to my Charter Cable VoIP service for the remainder of the week and I will try OBi again next week.
Update 20 April 2012: I re-enabled the OBI last week and have been using it as my primary phone. I haven't experienced any issues. I also increased the QOS priority for the OBI's Mac address on my router.