Don't forget the part where your brand-new custom framework needs to properly serialize and deserialize each value based on its type. Because according to this person: http://www.satine.org/archives/2007/12/13/amazon-simpledb/

...Amazon's magical indexing technology is to make all searches lexicographical. So you have to "zero-pad your integers, add positive offsets to negative integer sets, and convert dates into something like ISO 8601". Or something.

But at least you don't have to write one of those fiendishly difficult CREATE TABLE statements! Ah, "simplicity"!