It really didn't. The movie was alright, but by no means what it could have been, what the reviews made it out to be, or what I really expected of it. There's so much more they could have done, or things they could have done differently to make that particular scene better. A few things come to mind.
First off, the scene with the "berserker." Leonidas killed it way too easily. That thing needed to be chained up with 5 guys holding it to keep it from going crazy and killing persian soldiers, yet Leonidas himself can manage to prevent him from slashing him when he's on the ground. After he stabbed it in the eye, he kind of just sat there waiting to get his head chopped off.
Secondly, the scene with the rhino. Again, taken down way too easily. One guy with one spear takes down the rhino? It could have been so much more had a few more spartans jumped in and attacked it from multiple sides with the rhino providing some sort of a challenge. I mean, I can understand the elephants, they were at the edge of the cliff and had basically nowhere else to go, but the rhino? Should have been way harder to defeat.
Thirdly, the dude with the blades for arms and Xerxes. What the hell is up with them? We really should have seen blade arms get taken down by the spartans. For as cool as he looks, I think he should have been in the film for more than 10 seconds. And as for Xerxes, for claiming to be a god and as powerful as he is, he could have shown it. He could have at least done something - but he didn't.
Lastly, I feel there are problems with both the first 30 minutes of the film, as well as the ending. My problem with the beginning is that I understand that they needed to tell a story, but they really drew it out as long as they could and waited too long to get to the first action scene. After that instead of pure action throughout most of the rest of the film, we ended up with spurts sparsely mixed throughout. My problem with the ending was really the lack of an ending. Why was there was no final battle scene? Sure, a couple of guys got hit with swords, spears and arrows, but what's with Leonidas just sitting there ready to take the arrows? He just throws the spear at Xerxes and sits there waiting to die? Lame.
300 is by no means a bad movie, but for the amount of hype it got and what I was expecting from it, I came out very disappointed. For me it was average and mediocre.