The level available at E3 was the beach level. The new baddies were standard fare. They attacked and such. The flying ones could afflict you with slow when they hit you. One of the new enemies was totally cloaked. Though there was a distortion in the background wherever it was. After it was destroyed it de-cloaked and appeared to be some kind of robot. The heads-up display was redesigned and sported a new curvy look.
The big surprise in PSO is the N-link feature. PSO can hook up to a GameBoy Advance and download games to it. The 3 games shown were Chao Garden (just like in Sonic Advance), Puyo Pop, and NiGHTS. The game itself is almost exactly the same as the Saturn version. The Saturn game had circular levels and on the GBA they were just stretched out into a flat 2D space and when you reach the end you go right back to the beginning. Its great news to hear this classic is being revived.