You can still demolish a city, and the building actually get blowed up. But if you want to do it with rockets your going to have to play for a while before you research rocketry.
If it works on your computer I'd buy it, especially the DLC with all the unit goodness. I love the game dearly but have recently stopped because in my current game It's Me (Russia), Britain and The United Provinces. Any war is going to go across every theater, and hundreds of regions, and will require many years of military build up.
Fort sieges are kinda boring until you hit the late period, and downright easy after mortars. Cities are more enjoyable with their open streets and cover. But the AI is downright stupidly in love with Garrisons(loving to sit in a building till it's about to fall down or they're all dead), except in forts i've never had them garrison a building in a fort. The naval battles on Very Hard, are pardon but OMGWTFBBQ (Tried one as USA and got raped by the British), land battles are still easy but the AI still has some troubles, Campaign is annoying on VH go to war with one guy, everyone goes to war with you.
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...I've had a fistfight with two people on horseback though.