Buy this, even if you have purchased the first Pac-Man CE
If you do not go out and buy this game immediately, you are doing yourself a disservice. I purchased the first Pac-Man Championship Edition on the Xbox, and later on the iPhone because I enjoyed it so much. I was given an NES with a Pac-Man cartridge when I was three years old, and Pac-Man CE was most fun I have had with the game since I was very young.
When my friend told me I needed to download PM CE DX, my immediate response was "I already picked up PM CE twice, I doubt I need the new one." He urged me to get it anyway, and that it was still worth it. After some nagging, I begrudgingly picked it up...
This is easily one of the best games available for XBLA. It is leagues and bounds above the first Pac-Man CE. If you have ever enjoyed Pac-Man before in your life, you NEED this game. If you have never enjoyed Pac-Man, you still need this. It is unbelievably exciting, competitive, and best of all: rewarding. Taking down a string of ghosts is definitely the greatest video game moment of the year.
If I haven't sold you on this, ask anyone who has played it. They will tell you the same thing.