Completed it on normal today, then had a little play around with the unlocked content. Very nice, like the Mercs missions.
Same, just had a look at some of the extra content although I haven't unlocked that much yet really. The unlimited ammo on the magnum is nice

How do u unlock all the maps for Mercs mode?
Where are all the Blue Emblems?
I have 13 treasure items to find, any hints?
In RE4 the mercs maps were unlocked as you completed the first stage then second etc getting a certain 'high' ranking each time.
I think I only found 3/30 blue emblems on my first completion

I also have 2 and a half row of treasures to find yet. I will definately have a run through this again with the unlimited ammo magnum, makes things a hell of a lot quicker.
Overall a great game, I will try mercenaries later, if I remember from RE4 that was tough and it took me ages but I managed to unlock every character and get the highest rank on each stage with everyone, it took me agesss though. Looks like this and SF4 are the only 2 games I will be playing for the new few weeks/months.