Assault on Dark Athena is a pretty good package, giving you the original Escape from Butcher Bay, as well as a new (relatively short) campaign. What I would say is that if you're a hardcore shooter fan, I'd give it a whirl, as they've got some pretty cleverly designed gameplay sequences that you simply will not find in other popular shooters like CoD or Halo.
Aside from just a few interesting gameplay sequences, things are also kept fresh throughout the campaign with various platforming sequences, stealth, and first person melee combat. The first person melee combat definitely takes some getting used to and has a bit of learning curve, but it's definitely fun/intense and will make you appreciate having guns later on in the game much more.
