I bought this (along with Star Raiders) about a year after buying one of the first Atari 800's to ever reach New Zealand. My previous 'programming' experience was limited to an HP programmable calculator and 6502 assembly wasn't too hard to progress to.
First thing I wrote (over Xmas holidays) was a screen dump utility which I had done previously in Atart Basic. It worked and I learnt a lot in the process.
Have just (Jan 2008) bought an Atari 800XL, along with Atari printer, tape recorder and 5 1/4 drive for $44 (NZ) and can't wait to find another Assembler Editor cartidge