It's based on the Japanese build and seems pretty accurate (I left my Japanese copy at home so couldn't compare them when I was playing it at work). It's certainly better than the US version.
It comes with the DLC (Mega Black Label, which annoyingly I can't access on my Japanese version because I have a chipped Japanese machine

) and it also comes with the CD soundtrack that was released seperately in Japan. Cave actually recommended to Rising Star Games that it came packaged with an exclusive extra as it would persuade owners who already own the game to re purchase it again (they're well aware of their loyal fanbase).
Considering you can already preorder it for under £18 I'd say it was a bargain. Don't expect good scores for it though

The people demoing it to us didn't explain what the hit box was and didn't explain the scoring system either, which to me is crucial to get across when reviewing a shmup.