I use the older Hub myself and the call quality is excellent. I think with the latest models you do have to pay a small amount every year just to cover state excise taxes, but the old "Hub" was exempt.
Looking at the Groupon deal it looks like it locks you into paying for the "Primer Services" at $10/mo for one year. That's still cheaper than Vonage.
Family Rm: Samsung 52" LCD, Onkyo TX-NR809, Emotiva XPA2 & XPA-3 amps, PS3, Oppo BDP-93, FIOS HD DVR, Salk Song Tower-RT, Song Ctr-RT, Song Surrounds, SVS PB12-Plus/2, Velo SMS-1, NeoTV 550, Roku 3, Harmony-1
Bedroom: Hitachi 42" LCD, FIOS HDTV, Onkyo TX-NR906, LG BD370, NeoTV550, 3x Sierra-1 NrT (LCR), Boston VRX srds, Hsu ULS-15, SMS-1, Harmony-1
Home Office: Onkyo TX-SR707, 2x EMP E41-B, Emotiva Ultra 12 sub, and a small media server