a port as a PSNdownload or xbox arcade game would be awesome, coz i won't buy a ds just for that game.
My DS collects dust about 362 days out of the year but this will be a reason for me to use it just a little bit more. It will probably be the last DS game I ever buy considering that nothing really good comes out for this system anymore.
My 2 cents about why this is a DS exclusive:
SEGA probably chose the DS as the platform for this game because the DS has the largest user base of all the handheld consoles currently available. The game also looks a bit relaxed on the production level; what you have here is really just a standard 2D shooter. I don't think this game was very expensive to make at all.
Basically, a cheap game from an attractive franchise on a system with a large user base might add a little bit to the company's bottom line...and may piggyback on the success of A:CM when it comes out later in the fiscal year. It's a win-win game for SEGA with very little risk.
I think it'll be fun and reminiscent of Metroid and Contra but it won't be anything spectacular. I'm looking forward to it because games like Contra and Metroid are always fun no matter how many times I play them.