Great service -- sound quality is excellent, and it links to the same account as your phone-card style service so you can manage all your LD needs in one account.
Their new "SuiteAdvantage" service lets you get a US-based phone number for incoming calls, and is very well priced at $3/mo (2008). They’ll even transfer your normal US number (land-line only) to this account so you can keep your number.
Pros:
easy installation
cheap long-distance
no contracts
Few cons:
credit expires after 6 months, so you need to be on top of your cycles
seems to go offline randomly and without explanation
e-mails to their support line take days to be answered
They claim ATA support will be available "very soon" but have been saying that for over a year now. Meanwhile Skype has dozens of supported devices.
Also somewhat disconcerting is the company who made the phone softwarde, SJLabs, seems to have disappeared off the internet (along with their drivers) sometime in 2007. You can still find them via archive.org if you’re desperate (and patient).
Great product but I wouldn’t use it as my main line.