ImpII is an excellent game, but be advised it has nothing remotely comparable to TW's battles. (Then again, what game does?)

It does have a Risk-style campaign map, similar to STW and MTW. But if anything the AI is worse at fighting on it than STW and MTWs AI. Don't buy it if you want a wargame.

At heart, ImpII is a Civ-type game: research, build, expore, conquer. Where it shines is in reducing the micromanagement and in creating an a really tight economic model - you face multiple resource constraints, and surpassing them on hard is a enjoyable challenge. It also has a Civ-style competitive AI. Fear the Swedes. (Fear the Swedes?!? Nowadays that sound almost like "Fear Mother Theresa" or "Fear Kofi Anand").

ImpII is probably my favorite of the "strategic" strategy games (as opposed to the wargames like TW or tactical strategy games like JA2)