i've been using the magicjack for over a month now, placing calls all around the US, and it has worked reasonably well during that time. good enough, in fact, that i will be canceling my home landline. i would say the call quality is just as good as my cell phone (verizon razor) and on a few rare occasions slightly worse than a cell. granted, there have been two calls that were absolutely horrid and required i use my cell, yet all the others the magicjack did the job just fine.
overall i have not been super impressed or even completely satisfied with magicjack customer service. they're exceedingly polite and sometimes mind numbing and frustrating to chat with (no telephone support), but they really just seem pointless as they can't offer or do much of anything at least that has been my experience with respect to my few minor issue. i wasn't able to get my original area code (310), but i suspect that has more to do with availability in my area than anything else. i settled on the somewhat new overlay area code for Los Angeles (424), which isn't so bad i suppose. the other minor issue, is that i couldn't place an international call to the philippines during many attempts over the course of three consecutive nights and just gave up, even though, i paid $10 upfront to make overseas (international) calls. i have yet to try again so possibly it might work.
what else... well, although, i primarily use the magicjack with my macbook wirelessly, sound quality improves a bit with a direct ethernet cord connection. also some secured sites (fidelity, etrade, etc...) that i visit seem to bog or not want to work while the magicjack is hooked up. the chassis is cheap plastic so i wonder how long it will last before the mirror stuff starts flaking off. all in all for a little more than $4 bucks a month for the first year and less than $2 a month thereafter, it's easily worth it considering the cost savings and that you can use it anywhere you have high speed internet and a phone. i suspect this year alone i will save over $300 and call quality really isn't that bad.