Phones these days are becoming like the PC spec race of a few years ago, yes a quad core phone would be nice but would you really need it if you are going to use it for facebook or the next draw with freinds app?

Outside of the next gen of mobile games, you would be hard pressed to find something that these phones can that the n900 can't do aleady, so I would say go for it. The n900 is a wonderful little device that can do most things that you expect to do on your linux PC, granted in some cases a little more RAM would not go a miss but considering you can run some heavy programs such as GIMP, Iceweasel blender and open office you would still be very impressed at what this can do. Heck we have been using these for years and its only recently that the dual core phones have been able to do similar.

I would say go for it, you won't be dissapointed.