Not sure what it's like now, but the insides of the admin used to be fairly terrible (generating HTML with strings for instance).

There was a patch to change this to use templates, but it was rejected at the time as it slowed things down too much.

FormWizard (which I hear doesn't exist now), was a nightmare to use for any sort of complex form - I tried to do just this and had to call many private methods.

I understand metaclasses, but found the implementation of the ORM a little overcomplex.

Trying to use the ORM API to work out the structure of the DB was a bit of a pain last time I tried (had to call private APIs).