What's not to like?
There are many things that make me proud to be a gamer, and one of them is the homebrew/fangame community. To me, there's almost nothing better than a group of passionate fans getting together and creating something in honor of their favorite franchises.
A homebrew Portal for the DS fits the bill perfectly in that respect, as smealum has been working on a perfectly playable (although not complete) project that pays homage to Valve's amazing first-person-puzzler.
The developer states that it's all very buggy and doesn't have sound at the moment, but it works, which is good enough for me!