Although originally a great arcade game, the Xbox 360 version of Galaga doesn't give much more to offer.
Some players may be looking to download Xbox Live Arcade games for the Achievements alone. If that's the case, then Galaga is definitely your best bet. When I looked at all the Achievements, I found that most of them were fairly easy, and there were a few that appeared to be very challenging. However, I wasn't aware at the time that you could continue from each level that you complete. This made the game a little too easy, and even for a person like me made the Achievements much too simple and a little disappointing. Nearly all the Achievements that are available in the game can be unlocked simply by playing through the levels (which as I stated before can be continued after each one you complete, no matter how many times you die). However, there are three that are a little different, and involve the following: 1) Forming a dual fighter, 2) Shooting down a captured red fighter, 3) Getting a perfect bonus.
Two of the above Achievements mentioned are very easy. For those of you that aren't familiar with the original Galaga, forming a dual fighter is as simple is getting captured by a wasp, then shooting down the wasp with the other fighter you have. The captured fighter will then attach to your ship, thus forming a dual fighter. Doing this certainly gives you an advantage in the "Perfect Bonus" achievement. For some people, it may take a while to get this one down, for others, it may only take one or two tries. I for one, have gotten all of the achievements the first day I had the game. Sure, getting all the achievements doesn't mean I will never play it again, but that's really the only thing that the Xbox 360 port of Galaga added.
Even if you loved the original Galaga arcade game, you may be somewhat disappointed with the Xbox 360 version. It won't last casual players long, but will certainly boost your gamerscore up at least 185 if you put just a little bit of effort and a small amount of time to it. When it all comes down to it, the Xbox 360's version is nothing more than a bare emulation of Galaga, that will satisfy hard-core Galaga fans that are only looking for such, but will leave a lot to be desired for most gamers.