First of all, I want to thank dice for categorizing every one of those games (in color too!).
And it was a great idea to make the tiers more selective (50 votes for Essential instead of 20).
I've been playing Ninja Gaiden: Dragon Sword for a while now and I must admit, it is one of the best games I've played on the DS. I can't think of any other game with better graphics, and I love the non-stop hack-and-slash gameplay using the touch screen. In fact, this game gets the award for Most Damaging to Touch Screen, an award previously held by TWEWY.
Also, I don't believe I voted for Castlevania: Portrait of Ruin before because it was already an Essential in the old list. I'd like to throw my vote in for it since it's my favorite of the three DS Castlevanias, and I would love to see it in the Essentials.