If it's an ATV2 you'll probably get more than you paid for it because it's jailbreak-able.
I never bought the first gen ATV but when the new ones dropped for $99, I snapped one up as an impulse buy and then got another when the 1080p version came out, for the other TV.
I'm impressed with my FireTV stick (1080p streaming over wifi to the tune of 10Mbps for 2.5h straight!!, but I use the AppleTV more.
At $150, I'll probably buy the new one to see what it's all about. These streaming devices are pretty cool and pretty cheap. (I've also got a WDTV and my receiver does spotify+airplay audio; I haven't yet bought a Roku though).
It looks good, but the price is pretty baffling. I can run VLC and plex for free on my iOS devices, StreamToMe is $3, Air Video HD is $5. Is Beamer that much better?