The latest and presumably final DW: Strikeforce walkthrough from Koei details the new missions and tougher bosses.
Consoles will be getting over 40 new missions on top of what was included with the original PSP version, making the grand total 200. Of course, more missions will be added later as DLC, and if Koei's DLC habits with the PSP are any indication, they may even be free.
In addition to the ridiculously huge monsters we've seen already, enemy officers are supposedly smarter than before and dish out more damage, especially when they've entered a "hyper state" -- you know, when they start glowing neon colors. On top of that, you'll encounter legendary warriors in the battlefield (Lu Bu comes to mind) who can easily devastate your team.
Oh yeah, and Meng Huo. No one mention his wife...