All the maps are soloable but if you need to do one in a high level area it might be wise to take a friend or put up a call in PF. Some maps become much harder when wandering enemies are dragged into the fray, and one mistake will REALLY hurt. I believe the Cyclops does about 1500 damage if you don't dodge his swing, and the drakes breaths hit for several hundred as well.

My recommendation is to do at least a few with a friend until you're comfortable with the types of enemies, then tackle them by yourself.