Alright guys, I have finished Metroid Prime 3 now, making it the first Metroid game I ever finished.
It really was a good bit easier than the other two Prime games. After I had a couple of energy tanks, almost all boss battles were a breeze. The only one I died in before the final encounter with Dark Samus was against Gandrayda, and that was only because I only had for energy tanks left (You can't save before that battle for those not remembering).
The last encounter gave me something to bite though, I think I had to try it five times. The first time I was almost dead after Dark Samus, the second time I died during the second stage of that battle. After that I could always enter the final stage with quite a lot of energy left, but I had trouble against the head. During my final (succesfull, thus final) try, I changed my strategy a bit and could win the fight with ease. I don't even understand anymore why it took me so many tries actually.
However, I really enjoyed the game a lot and now I am even more looking forward to Metroid: Other M. And to finally answer the question of this thread, I would say that Metroid Prime 3 is a game with a good amount of difficulty compared to most other games on the Wii this gen. Compared to its precessedoers however, it is quite easy. This should make it clear that the series can considered to be hard.
Mission completed.







