I think it connects well with something I loved doing as a kid, and that's playing with army men and action force characters. Its great, and I somehow never seem to tire of watching the units fight in melee. I'm already hoping for a Shogun 3, but I know that won't happen as it probably was a really slim chance that we'd even see a sequel to the original Shogun. 
 
Since its release its been treated to some okay patches, and I've never encountered game-stopping bugs in singleplayer. I've hardly touched multi-player, and that's where I believe they've had some issues like the game falling out of sync. I've spotted patch-notes in that regard so perhaps its been improved. 
  
I can't wait to see what the next game will be coming out from Creative Assembly. A lot of people want Rome 2, which I can totally support. Supposedly ranged-combat isn't too well captured in these games, but still I'd really like to see a futuristic game with lasers and mechs and whatnot. 
 
Anyway, I recommend Shogun 2. Once you get better at the game and understand the units, its a real test to progress through the difficulty settings. I've played a lot and I haven't been able to beat any campaign on Very Hard yet. Legendary is the notch that is tougher and that's near-impossible, or so I think anyway. In Very Hard it sometimes feels like I could have a slim shot, but hehe I'm not good enough I think.

I tried the demo, but couldn't really get into it. I kinda feel it's a bit too slow, since I like my RTSs fast, so maybe it would have been better for me if it was round-based.

That's just my opinion though, I can totally see how the slow pace and the strategic placing of units that comes from that can be appealing to some players.