If you want something that gets your music and photos on your tv with zero hassle (especially if you are a mac user I suspect) the I think aTV is a winner. It doesn't have the functionality that doing this through a mac mini will give, but that depends on how long you want to spend doing this, your technical ability in this area and getting it to work.
I bought an aTV when it first came out at 6pm from the local apple store. In the early evening I was watching stunning photo albums and playing my iTunes library through my BV6 - and I am not a computer whizz at all.
It depends if you want low hassle and something that does what it says on the packet (and no more) I think its a winner. Plus the YouTube addition is something I can play on long into the night - and the videos look something else on my 22" B&O screen compared to a laptop.