I like 4e because it is "fresh" and "new". I've been playing D&D a long time, and I have had fun with every edition from 1 to 4. I enjoy playing games, and new games are even better.
I have been playing 3e weekly since it came out. The games are still fun, but I have grown a bit tired or burnt out. Every edition has brought something new to the game. I recall thinking how much 3.0 brought to D&D, feats were the coolest of the cool.
But this time, I feel 4e really changed things. It didn't just just add more stuff to the pile, but actually made changes in how the game flows and feels. It brought the fun back into playing the game for me. Sure, a lot of the fun in D&D is just role-playing (which is mostly system and edition irreverent), but combat is system specific and I just like how this new game plays.
Also, as many have mentioned, I find this version easier and more fun to DM. Sure most of the creative work is the same, but it seems much easier to run and less work to create.