I don't know if any of the recent updates fixed the balance but on launch it was a very hard game.
No, it's still pretty difficult. Around stage 2 of the DM Land or something, there's always that one room with all of the orc berserkers and for the life of me, I cannot get past it with just the bots, who are far tankier than actual players.
DM Mode is still pretty ridiculously easy (Resurrection tower OP), but since you get more points and gold with longer matches, I get the feeling that DM Mode isn't intended to just allow you to stomp your friends into the ground, but it does give you some very good chances to be a total dick to your friends.
That's the way I'd probably try playing it, though. Have fun getting past resurrection tower, a beer tower, and a spawner. Actual players could probably do it, though. The bots always wander around taking care of the miscellaneous enemies before trying to kill the resurrection tower, so they always take lots of time getting through it.
At this stage, I think they probably do need to tone down the difficulty a bit so that "normal" is actually normal and easy isn't so hard.
EDIT: Looking at the steam forums for the game, it seems that the devs are very active right now in the community and are paying attention to both the difficulty and several FPS/bug issues. Dungeonland might get far better in the future.