The best way to find out is to try. There have been definite improvements in AI and added features since launch. version 1.5 represents 5 full passes of development and balance. A lot has changed. Whether it is enough for you is a question only you can answer.
+1
Since you've asked specifically about AI - it is better. Like you I played a bit in beta and a small amount shortly post launch then put it down until the 1.4 patch. During 1.4 I put in probably 50 hours and quite enjoyed it.
Fire it up and give it a go, if it's not there yet you can always just put it on the back burner for a few months.
hope this helps, cheers..