So far, the only difference between the old and the new Apple TV is size and price. The new Apple TV is really tiny and still has a built in power supply (!) and at 99 USD it is a very affordable device.
For now, it is only for sale in the US. Does it work in Europe? Yes, it works well with 220V and 50Hz and a European flatscreen TV.
Is there any point in using it in Europe? No, not really.
If you live in the US and have a US iTunes account or a Netflix account, then you can use the Apple TV to rent movies and TV shows. It's quick, easy and fairly cheap and the image quality is good.
If you don't live in the US and you have, say, a Finnish iTunes account, then there are no movies or any tv-shows available for rental. And in this case it is quite pointless to have an Apple TV. You may be able to circumvent the regional restrictions with a fake US iTunes account but it is cumbersome and if you are caught you might be cut off.
You can use Apples "home sharing" to stream audio and video from your own computer's iTunes library to your Apple TV but the device is just as picky as before about video formats with only certain variations of the MPEG4 video format supported.
Eventually Apple will secure the rights to distribute tv-series and movies in more and more countries but it will take years.
More interestingly and in a more immediate future, is the possibility that Apple will start making applications (apps) available for the Apple TV. It's built around the same hardware as an iPhone/iPod touch but without the touchscreen. With low price and free games and utilities the Apple TV would become a really interesting home entertainment system. Perhaps the Magic Trackpad that Apple recently started selling paired with an Apple TV would be the perfect way to to turn your TV into a giant iPad on your living room wall.