Synaptic is a major improvement over the original apt tools -- while it's slower, it actually handles dependencies correctly most of the time, and doesn't throw anal-retentive errors.

Unfortunately, the underlying apt system has plenty of shitty behaviors that aren't even related to Debian's shitty packaging policies or the hostile original implementation:

  * Only one process can even read the db at a time!
  * It's extraordinarily fragile
    * Loves to crap out at the slightest network failure
    * Will corrupt its database on SIGINT
  * Hamhandedly muddles up installation and configuration
  * Does not handle optional dependencies well
  * Poorly handles only part of the 'alternatives' problem

A lot of its failings are rooted in the assumption that installation will be fast enough to be interactive, so why bother?