About Metroidvania games, I'm not exactly love it, but I played few of them.
I started discovering it out of accident while browsing a new game to play; Castlevania: Dawn of Sorrow, J2ME version.
At that time, I never know the game was a ported version of the DS version (as I never have it before), and I'm really impressed with many things, specially seeing how the mapping system works on the 2D platformer-ish games.
The second game I tried is the prequel of Dawn of Sorrow itself, the ported version for older mobile phones (or J2ME); Castlevania: Aria of Sorrow. The game is... quite stuttering by low framerates, but I managed to complete it without any single clues what's going on. Comparing with the two, while this one is worse in graphics, but it managed to provide slightly more contents to the game.
And then, many years of silent, I got a new phone (which still used to this date, even for writing this), and knows about emulation, I tried Metroid Fusion. At my first impression, I have no idea about the story, and after playing it a bit, it looks like some overly sci-fi games (which I'm not into it that time), but I immediately love it as this one can be a horror game by being chased all around by SA-X when least expected. About how hard it is, it's decent. It took me few times to beat the final boss, but I did it.
After that, I tried the other Castlevania games. While I like Portrait of Ruin, I think Order of Ecclesia is much more worth mentioning for some reason.
Castlevania: Order of Ecclesia is an interesting one for me. I love the glyph system, and as well with different maps to play (even though it's not as good as how Portrait of Ruin implement it). I sometimes saw few comments that mentioning how hard Order of Ecclesia is, but for me, it's not really that hard, as I managed to beat Dracula the second time without weapon/magic with light attributes.
I think that is all I can pour my thought about Metroidvania games. I did played much more of them, but it's probably just a rom hacks, so I don't want to mention it here.
Thanks for reading up to this point, and have a nice day out there.