-New way for Light to first meet L; instead of being introduced at university, L instead calls him to get him to join the investigation team. He then leads him through a series of complicated rooms and whatnot to meet him in a big screening room where they watch some Kira evidence together.
-The full version of Zetsubou Billy plays from the moment Higuchi goes to write the policeman's name down to when he gets captured, as opposed to the normal music.
-There is a single shot of the ceiling when L dies that was not present in the original. I don't even know why they added it.
-There is actually a really nice scene at the end where they make a grave for L and funeral and stuff. The rest of the team walks off and Light stays behind, taunting L and physically defacing his grave, saying "I HAVE WON", etc, etc. This was a really good scene.
-Oh, there was a new introduction where an unknown Shinigami comes to Ryuk to hear about Light's story.
-We see after this that the unknown Shinigami has left, and Ryuk tells him to drop a notebook in the human world if he wants some fun, ending with the words "Isn't that right... Light?" which I am not sure if he is implying the unknown shinigami is Light reborn or not, I dunno.
-There was a different version of Alumina for the ending credits
-You'd think they have the bloody decency to at least not recycle animation in their NEW GRAVEYARD SCENE, but no, no, they went and re-used stuff from Episode 37. Light's maniacal laughter when he claims "I am Kira" to Near and his eyes are glowing red is recycled for this scene, but his eyes glow blue instead.

And yeah, that is about it.  I mean, the Near/Mello arc wasn't even covered at all. They also chopped out A HEAP of stuff, so if you're watching Death Note for the first time, chances are you will not understand what's going on. They missed out several plot points that bring it all together. I don't really know who the target audience for this was, considering it was aired a mere TWO MONTHS after the end of Death Note TV, so it's not like people are like "Oh yeah, haven't seen for a while, might just catch this one to refresh my memory".

I had always assumed that when Ryuk said that when Light dies Ryuk would write his name down and that he wouldn't go to heaven or hell to mean that users of the Death Note are reborn as shinigami.

Also I am sad to see that they did nothing with episode 37.