I've used ATV for a little over 2 years, but only in the states. Overall I really like it a lot, but as someone else posted it's more out of convenience. I have my iTunes music and pictures streamed to it, in addition to renting movies and watching YouTube. When I change the input on my TV a collage of my pictures scrolls.
Now, the hiccups. As others have mentioned there is another update coming. I've updated my ATV since the first version. I loved the first version. I could rent and download movies in about 4 minutes over my wireless internet, and sync to my computer no problem. Then the new updates started rolling through, and I had syncing issues. Then the next update came through, and it would literally take like a day to rent and download 1 movie. Apple swore up and down that it was my service provider, but I have two other computers on my network that could download without any problems at all. However, this last update that I did seemed to correct all those issues, so I will keep my fingers crossed on the up and coming update.
Lastly, if you can afford to drop a couple hundred, and want a cool convenient toy do it. Otherwise, just get the cable, plug your laptop into the TV, and rent from iTunes that way.