"Ultimate HD includes the Encore expansion, as well as all the extra towers, enemies, and levels from the Deluxe edition last seen on PSP."
The Encore expansion was also part of the Deluxe PSP version by the way, so it looks like this is just a Vita-enhanced port of that with touch control, check points between attack waves, and trophies. No mention of new levels. It's a little odd, since the PSP version already plays and looks great on the Vita.
Still pretty groovy.
(Full Disclosure: our podcast Go For Rainbow! is named in reference to PixelJunk Monsters!)