To start with its identical to the arcade original, no Saturn assets here at all. This in't down to the visuals either but also all the functionality (timings etc.). There are a few issues of z-fighting on some surfaces but it's very rare and most were in the original too.
There are a buttload of options in this version too, they've got proper alpha on the textures (but that makes the game a lot harder because you can't see certain attacks properly), a very nice widescreen mode, the various Model 2 resolutions for the A, B, and C boards (!) and obviously a progressive scan option.
The secrets menu is just messed up, so many dirty options (you can play as fucking Z-Gradt if you want to, which is very satisfying) and they've included a bunch of special moves that were featured in VOOT (such as Raiden's crazy armour break). Chibi mode is also a laugh but the size actually messes up my reflexes in terms of the ballistic arcs of the shots.
Overall, it's a beautiful conversion and in many ways supercedes owning the cabinet...well, almost...
The one big problem with the port is the lack of TwinStick support. There is the dual analogue stick setup from Marz but it's just not anywhere near
as responsive as it needs to be (though it is very playable still, even more so than the Saturn version). Marz got away with it because the game was much slower and wasn't about ninja timings. The original, by contrast, is ALL about that.
I am in half a mind to use a normal face button setup, just to get the controls up to a speed I'm used to, but in the back of my mind it feels a bit wrong.
Bizarrely, the game supports the USB Saturn pad from a few years back. May need to track one of those down or try and hack a pair of Saturn sticks...
Managed to find a secret boss in the new port:
http://uk.youtube.com/watch?v=zgxXcz2p1TA
It also seems I'm the first one to have found it (the Japanese VO community apparently completely missed it).
To be this good takes AGES!