Been playing Pokemon Platinum since it came out. I love it, but then again I'm a Pokemaniac so I love all the main series games (Pokemon Ranger can go jump in a volcano).
Also been playing Phantasy Star Portable. It's my first Phantasy Star game and I'm thoroughly enjoying it.
One more thing, I also picked up Avalon Code for the DS and it's definitely going down as one of my all time favorite DS games. Aside from minor annoyances involving MP consumption it's a game that I'd highly recommend to any DS owner.