So far with 2009, Reference Manager seems more stable
The quick properties is neat but causes quite a bit of overhead on resources to negate its usefulness.
Unless you have a dual or quad core machine can't use it.
I like the ribbon system in concept, but the cui is lousy at editing it.
I have to close down and reopen AutoCAD completely every other edit,
otherwise the cui acts like it is doing something,
wastes a bunch of time, then does no changes when applied......
Also the ribbon seems to only do AutoCAD/MEP's stock ribbons or my custom ribbons.
Refuses to mix the two for some reason which sort of kills any potential for adoption.
The Enterprise cui and standard MEP cui seem to be in conflict constantly.
Some things seem faster, and I do like the quick standard toolbar being editable.
I have had fatal errors occur but the system did not crash and close. it continued to work.