If it turns out the port has the same worse quality as the PC port I am afraid it won't run very well. The PC port suffered from various performance problems (slowdown when fireing, slowdown if there are more than 3 enemies onscreen, mostly in indoor level).
These performace problems are related to the overuse of various pixel shader. It seems who ever made the port thought: "Well, we can create a ok looking shader effects with three lines of code, why should we care about high-res textures?"
Honestly I have a meaty system 'Athlon 2600XP, Radeon 9700, 1 Gbyte of RAM, 80Gbyte HD and hadn't problems with recent games (except Halo). Furthermore a lot of people report the same problems. Simply do a search at the penny-arcade.com forums.