Act 1: It started with some fun little quests to introduce you to the narrative style. The fights were too hard, so I improved my character stats until I could handle them. It's not easy to know when there's no choice but to go along with whatever is suggested, and when you can do something else, but I guess I got it more or less right.
Act 2: A nice meaty dungeon crawl. My efforts to make my character stronger paid off, the difficulty was just right.
Act 3: Holy shit it's too hard suddenly. One does not level up quickly in my version of Skyrim, maybe that's why. At one point there's an option that suggests you can skip the whole thing, but I didn't take it and would guess it probably isn't so easy. I had to resort to stealth archery and I didn't bring a lot of arrows. Some horror game stuff of a kind I don't normally enjoy, but it was well-executed. It was a pretty long slog.
Act 4: Okay we're in Dark Souls now. Except the boss fights are even longer. I had a legendary weapon, shiny superhero armour, lots of magic resistance, a good healing spell, all the equipment a skyrim paladin could want, and yet even some of the non-boss fights took a lot of time and effort. Hit, dodge, run, heal, repeat. Forever. To be fair I do have the difficulty settings turned up pretty high. I wandered around lost for a very long time. Some of the battles were epic. There was only one area I had a really hard time with: There doesn't seem to be any resisting the tentacle attacks so they were pretty much instant death.
The ending was quite good and made it all seem worthwhile.
I've used them both in the past, but prefer Xfce now. So I'm probably not too biased either way on Gnome v. KDE. I'd say they're both extremely well-supported, popular, respectable, and safe choices. They're quite different in style though, so odds are you might find you have a preference for one or the other. Go with whichever you like best.