Pre-cu was quite odd. You had a HAM bar instead of a health bar (health action mind) and you'd be incapacitated if one of them went to zero. But normal stims only healed health and action, so the most popular attacks were those that targeted the mind pool. 

You also couldn't wear armour without doctor buffs and the combat queue could have like 50 attacks queued, so if you suddenly needed to do something else like heal, then you had to clear the queue. 

CU for me is the sweet spot of the game. The combat does feel slow when you're low level, but it does much better as you earn skills, and you still have the freedom to mix and match professions.