In that it has pine trees and lakes, very. Otherwise, not at all.

Effectively all finns left Karelia after the war. Those few who did not got moved to some shithole in Siberia by Stalin.

edit: This is what Stalin did to most non slav peoples in Russia close to any major/important city or resource. (in this case Saint Petersburg)

I don't think Russia has really made any efforts in Karelia, so it might basically look the same as when Finland lost it 80 years ago.

There are few. I have friends who go there a couple times a year to bring clothing and supplies.