The speeds detract for me because it limits the time to enjoy a battle, leads to increased pause use, and in the end detracts from good strategy in the game. A slower pace, particularly movement speeds, would make it more enjoyable to think my way through a battle without pausing.

The AI is not great, but it works. However, when playing through a campaign the weaknesses become so apparent that many battles are a chore. In MTW at least, maps were varied and distinctive enough to prevent repetition, and the AI would pose a decent challenge in most cases; both factors together made for memorable battles, far moreso than in RTW.

So yes, both factors detract from my experience.