Viking: Bought it. Finished it. Loved it. As far as trickiness goes there was only really 1 main area that was a right bitch, a couple that were tricky but tolerable and most of the rest was do-able first time. A few of the trinkets you have to collect were in right sneaky places.
Overall I didn't get 'frustrated' in the traditional sense. Lots of checkpoints everwhere so you knew the next part was going to be tough, but possible.
I heartily recommend it. Plus for achievement whores out there, there are some challenges to attempt once completed. Severe challenges I hasten to add...
Did you get past The Final Challenge? I am stuck as hell at that part, which is frustrating, because I KNOW I'm right at the end, but I can't figure out how to get past those flippy gates in the right way to avoid the edge of the screen and other spikes.
Also, this game is satisfying as hell. Even though I have 973 deaths so far, I just keep coming back at it. It doesn't seem unfair.