After reading Tasty Pastry's review, I felt that DIG DUG didn't get the respect that it deserved. I bought this game for 400 MS Points today, and I completed it today. With that said, I'm not disappointed in the slightest. When I bought this game, I wanted a blast from the past, and that is exactly what I got!
The achievements are fairly simple, and some are a little repetitive, (drop 2 boulders, eat the fruit) but honestly, I can't think of anything else that they could have added as an achievement. They were forced to make these repetitive achievements because there really isn't much else to do in the game! They had a few other achievements like clear an entire area, and crush X amount of enemies with 1 boulder, both were fun to do. The one thing that made me a little annoyed was when clearing the entire play area, you have to walk across everything, including the parts that start off clear.
In conclusion, if you are thinking about purchasing this game, know that it is an old arcade title that they brought to the XBLA. I bought it to re-live the old days, and I didn't want anything new added to it.
Lastly, if you asked me to recommend an old arcade title, I'd recommend this before I'd recommend Pacman C.E. because I enjoyed DIG DUG much more.