My understanding is that appleTV gets material from your Mac computer so why not just hook up the mini direct to your TV via DVI to HDMI or s-video ? No need to transfer files over a wireless network because you have them on your harddrive or just slide in a DVD. A bluetooth keyboard and mouse now you can surf the net from your couch 
TV half the price of mini. DVI->HDMI carries video not audio so no HDMI receiver with 1 cable. Simple set top device that you just plug in so no need for keyboard. All depends on what you want. For some, a mini is the right choice. Others, an 