I have a 32 GB asus t100, with a 32 GB SD card, and have about 15 GB free overall despite a full complement of software. 64 GB is doable, especially now that they've changed things so you're not losing space to a recovery partition. Doable, but not great, just like the 2 GB RAM.

I may end up replacing my t100 with the 128 GB surface 3, especially given the small price difference.