This expansion (both really) are worth having. All of them together still fit in the base box. The addition of short and long term goals really does add a lot to the game by offering even more choices and paths to victory. I highly suggest it.
The best Race for the Galaxy expansion! In addition to offering new cards and start worlds it also provides the ability to play a solo game as well as add some depth to the multiplayer game. Lastly, it adds the cards needed to add a 5th player. My favorite part is the goal tokens which usually give a player victory points for having the most of something or the first to achieve something. It really adds to the base game. If you like Race, there's no reason not to get this. Enjoy!
I don't usually like game expansions (rather have a new game entirely), but Race for the Galaxy is great enough that you eventually want more. Between the expansions, this is our favorite addition - it adds a lot in many little ways and keeps an excellent game from getting stale. Also fits in the original game box!
Add more to the "Race" with goals that give bonus points to the first player to fulfill them and also "longest road" style goals that you can steal from other players. Most importantly there is more starting worlds and phase cards to support an additional player. This expansion is a must!