I'm making the switch from Comcast to MagicJack for my so-called pseudo "land line."
I have it running on a cheap Fit-PC Slim that is running the MagicJack software only, nothing else. I figure the $235 I spent for the Fit-PC Slim will be paid for pretty quickly due to (a) saving $25/month when I get rid of my Comcast line, and (b) running the MagicJack on a dedicated PC that sips power (it runs on only 10 watts!), rather than on my main PC that is an i7 behemoth with tons of cooling, etc. I can turn off my main PC when I'm away from it.
I have MagicJack voice mail messages e-mailed to my Gmail account, and from there I have a Gmail filter set up that sends a text message to my cell phone when a MagicJack voice mail comes in.
My Fit-PC Slim is remotely controlled from my main PC, so does not need a mouse, keyboard, monitor attached.
The MagicJack interface and the ads on the side of the window don't bother me because (a) I'm not using the interface at all; the MagicJack PC just sits there and does its job, functioning as a phone, and (b) I installed MagicBlock and MagicWho? to make it as invisible as possible.
So far, so good. The sound quality is at least as good as my Comcast line if not better. I'm hanging onto my Comcast line for a little while pending some more testing, but am expecting to get rid of it soon. Looking forward to the cost savings.