Ok... so there is a couple of quirks but I can live with them.
first, Plesk's php enabling doesn't work. It uses the wrong type of test to see if the php module is installed:
Plesk uses:
<IfModule sapi_apache2.c>
php_admin_flag engine on
php_admin_value open_basedir "/home/httpdocs:/tmp"
</IfModule>
When it should be:
<IfModule mod_php5.c>
php_admin_flag engine on
php_admin_value open_basedir "/home/httpdocs:/tmp"
</IfModule>
And of course Plesk doesn't use templates... all that is hard coded into a binary file. So I have to enable PHP by hand...

The final problem which is also very annoying is the updater utility doesn't work. It tries to reinstall PHP4 and a bunch of other things it doesn't need. So to update, I have to download it manually and apply with the --nodeps flag.
Thats it.. Webmail works, adding delteing domains work as well. Everythign works perfectly other than the 2 above quirks.