Just did an upgrade to my current home theater setup by replacing my old Mac Mini with the new version. First impressions... Very impressive. Aside from the slimmer design (and included HDMI port), the playback performance was noticeably better. Mind you my old Mac Mini (2ghz - 4GB RAM) performed like a champ but had stuttering every now and then. Not so with the new model even with 2GB less RAM. Another thing I notice when ripping movies with MakeMKV was that I would often get the alert that my hard drive was not writing as fast as MakeMKV was ripping. Not so with the new model so I'll assume Apple sprung for 7200rpm drives instead of 5400rpm ones (can't confirm this though).
All in all, if you're planning to get a home theater PC, the new Mac Mini is the best offering I've seen on the market. To save a few bucks, get it from Amazon where it's $30 cheaper and no tax plus free shipping.