I like it! It captures a lot of what is great about Metroidvanias, but I still feel like it is missing a lot of nuances. It also fails to address some of that things that bug me about the genre.

GOOD:

2D! It is great to have a 2D metroidvania on a full console. It is getting me pumped for Other M.

The map is good, I like that you can turn on and off the guide (here is where you go next) line whenever you want, though I wish that the guide line weren't necessary.

It adheres to the genre well, and it is an awesome genre imho, so it ends up fun.

Has cool acchievements, and some extra gamerscoreless ones which indicate that the game has depth (you can complete it with only about 5 items aparently!)

BAD:

Sometimes the graphics interfere with the gameplay :(. Mostly they are great, but other times it is really hard to see where you can go, where you can shoot/be shot from, where enemies are, etc. The flashlight is a great touch though, but why does it need a draining battery like the flashlight in HL?

The bosses suck. At least so far. The first one I just basicly stood there an shot it untill it died. I'm playing on normal, but still. They don't really have patterns or weaknesses to learn, which are basicly required for metroidvania bosses.

No music! One of the things that makes Super Metroid and SOTN awesome is the music. This has very sparse, generic music.

Lock/key item usage. At least the items I've gotten so far seem very lock/key style, every metroidvania is guilty of this to some extent. The thing that bothers me most here is this. Grenades seem to fill the roll missiles did in Metroid. There are certrain doors which need to be opened with them. In Metroid though missiles are also very useful in combat. Grenades aren't so much, often the enemies are in the background, and while you can shoot back there, I havn't found a way to chuck nades back there. There are some nice 'nade combat moments, but they are scripted, and again, lock/key-style.

SIDE NOTE:

The style feel like a less polished MGS1!