It's fun and it's frustrating. There is only one word to describe this game... funstrating.
The story is funny. It involves Matt Hazard, who is basically a Duke Nukem parody. He left the scene for a while, and now he's back. In real life, he was never in the scene to begin with, but that's another story. His game starts to mess up and it turns out, the evil creator (voiced by Neil Patrick Harris), is planning on killing him in the game, that is until he meets a special friend who helps turn the game around. It features numerous parodies that will surely get a few laughs.
The main issue is, all of the things it tries to make fun of... are present. Level designs are all based off of other games, and for the most part, they're totally generic and lame. Why? You may ask, because it's attempting to make fun of them. Parody games don't work well. Mainly because the things it's parodying, you have to play through. So all of the flaws featured in games that Eat Lead is making fun of, you have to deal with.
But hey, the games pretty fun. It's totally generic in terms of gameplay. Stay in cover, shoot out of cover, run along, repeat. It adds a couple mediocre, not-that-fun mini-games now and then, but they don't spice up things, but rather make things more annoying. However, all of the different weapons and enemies make this a lot better. A lot of games like this feature a select few enemy types. Eat Lead features 10+ enemy types, some of which take different ways to kill. The water gun swinging enemies take more damage when attacked by water guns. The Halo esque enemies die a lot easier with the futuristic sci-fi weapons. Other enemies die other ways too. One of my favorites were the nazis (who were obvious Wolfenstein parodies). Since they're 2-D characters in a 3-D world, you can't shoot them from the side, which makes killing them a lot more interesting.
Boss fights are hit and miss. Some, like the sniper, are annoying and frustrating. Others, like the Sephiroth rip-off, are amusing, mainly because it changes things up and makes the game like an action/turn-based RPG hybrid, which I enjoyed. The last boss was pretty annoying, seeing as most of it was killing his lackeys, then attacking him. You know, rinse and repeat.
The games cheap. Enemies kill you in the most annoying ways that will make you scream "WTF? THAT'S STUPID" after which you go in corner and cry about how unfair the world is... or maybe that was just me. Enemies pop out in corners you didn't know were even there.
Overall, Eat Lead hits a lot of the right notes. It's fun and it's certainly funny, but it's also completely frustrating and generic. I try to forgive it because it's hard to make a parody game without it being like every other game, but I can't. I can't enjoy things that I don't like. Eat Lead is best left as a rental, seeing as it's pretty darn short, with little replay value.