My Doom Levels e1m1

This is not my first map ever, just a replacement of the original e1m1. After gaining some amount of experience with Doom Builder, I decided to just go ahead and start making a series of maps, and I started with this one. Each map, I am hopefully going to stay away from really gimmicky things, in general. But I want to always have at least one secret, some monsters, and I will place items that count towards the item count around the level. Most importantly, I want them to be fun and have good gameplay. Since this is just the first level, I wanted it to be pretty short, and easy. I thought of having no key, where you could just run to the exit, but what I have done is straight-forward enough. Some things I may change someday: the textures of the starting building, and their alignment; not having a bridge to the key (just lowering its platform); make the secret area easier to find, etc. The music is an midi version of Cowboys From Hell by Pantera. It seemed perfect for a first level song. Let me know what you think.