Action still holds up after all this time. Great collection (but leaves out Life Force).
You'll also enjoy the rapid-fire button options for gunfire/missles -- something I used to need to borrow my friend's Advantage joystick to make use of on the NES. Other editable options include adding extra lives (up to 9) and variable difficulty settings.
The only real knock against this PSP collection is that you have to play it on your PSP. The handheld's wide design wears your hands out, and an intense game like anything in this collection will quickly make your fingers and knuckles sore.