My understanding is that "faster" simply refers to an all-new on-screen experience which includes one-stop search, but the actual processer is not any faster than the XS. Also the same "faster" interface will be available via an update in May 2013 for the XS and other Roku models. So no difference there.
As far as the remote, the Roku 3 has a headphone jack in the remote. For some that may be awesome. Personally, I would rarely, if ever, use it.
Wrong, the CPU is faster in the 3 vs the 2XS model. The headphone jack in the remote is a cool novelty feature.
It now supports gigabit ethernet, and dual band N wifi.
Is it a huge upgrade over the 2XS? Probably not, but if you don't have one or are using and old roku 1st gen then it's probably a good deal.