If you're a fighting game nut then, and don't own a Last Blade game on any other system, then I guess go for Last Blade.
I love fighters and have a whole bunch, but I just couldn't really get into Last Blade on NGPC too much. For the same price, or probably even cheaper, the Dreamcast version of Last Blade 2 is readily available and it's a far superior version of the game.
If you're looking for another great fighter on NGPC, then go ahead and check out Last Blade. It's definetly a good game, however, like I said, I'd recommend Gals Fighter and Match of the Millenium over LB any day.
Get Last Blade if you want. Just make sure ya don't miss out on Crush Roller.