No...not better at all. Different is a better word.
Yes, D2 is *easier* to play games since it has the decrypter built in, but there are also a few bugs that make it a little less reliable than m33-6. Sound issues on occasion (no sound to be exact), some serious VSH menu tv-out issues (it's buggy as hell...you can tell it was an obvious m33 vsh menu hack), as well as some issues with mounting video ISOs (sometimes it does not see them) and of course no memory card speedup...which is useful for CSO playback.
So, in my personal opinion, m33-6 is still better overall.....as long as you invest the time to manually decrypt your games. You have two choices:
1. Use D2 and deal with the issues. You can play all of your games without intervention which is the plus.
2. Use m33-6 and have no issues except for dealing with decrypting your games manually.
I use option 2, because decrypting takes literally a minute and it is done and working. I'd rather do that than deal with the various issues I mentioned. Don't get me wrong, D2 is a good firmware. Just isn't up to par still with m33-6. Maybe Gen-E will have me think otherwise