Mr K did a fantastic job with his Kawaks port. All the larger roms that I've tried run smoothly without any hitches, and I noticed that the analog stick for the original Xbox controller is surprisingly responsive. Even with SNK style super motions.
The implementation of virtual memory is a huge step forward for homebrew Xbox development in general. Provided that Mr K is willing to reveal how he did it, I can't wait to see how other developers will take advantage of it.