Nah, I have no issues playing any home system that isn't an NES, so it isn't that. Like the NES controller, the DS Lite is a rectangle with no grips or ergonomics, so it isn't comfortable for me to hold.
Even if a used system were kept in good condition, there is no telling how much use it actually got, so it could face a host of potential problems in the near future. It isn't worth the risk.
I used to own a DS so I have an idea of some of its games. I'm not going to find anything like Super Mario Galaxy on the DS, but this topic isn't about that so I won't go there. I want one mostly for RPGs and puzzle games since the Wii is pretty lacking in both those genres.