MTW vs. M2TW?

[Martok]

hows the AI as compared to Medieval total war, better, worse, etc?

The AI in MTW is better, especially the battle AI. The gap between the games' strategic-level AI is narrower, but MTW still holds the overall edge (it handles the Risk-style map better than Medieval 2's 3D map).

i'm probably getting the first one but i want to see what number 2 has to offer. is the movement system still frustrating? Is the map cartoony like it was in Rome or more realistic like MTW?

Personally, I find MTW to be superior in both regards. This is admittedly a more subjective issue, however, and I'm sure that just as many (if not more) will say that M2TW is better. Either way, your mileage may vary.