Any game needs to get used to it to become easy. So I DO think this one is very hard on 'normal', at the begining. This is not a game to enjoy it for years and years. Because once you walked through the not very long story once or twice, there is not much novelty there anymore, no incentive to replay, so you don't really have such a long time to get used to it. So, why bother with the hard fights, since, as intended, it's the story i'm interested in? The very hard fights distract me from that story, and I find them annoying.
These were my first thoughts. However, once I started to gain levels and upgrades for the weapons and armors it became much easier, which added to the fun factor (for me). For the moments I want to be a click freack I have other games. Serious... Serious Sam, I mean... :)) Yes, I still play it, sometimes, briefly, just for the difficult and funny fights :)