Not too great.
It seems to have many flaws.
I don't personally know if the weapons shoot, but from what I have seem, they are just held out, and you have to get in touching range to hit an enemy. Having more enemies and a weapon that shoots wouldn't be a bad thing.
The graphics look horrible. The mix of 2d and 3d does not make this look well. The enemies and master chief both look poorly done.
MC also sinks into half of the platforms, some over half way into them. It also seems as if some platforms have two layers, meaning he will hit a platform, stop, then fall and hit the second layer of the platform, which also sits in the middle.
You have a large deal of work to do with this. I suggest trying to clear many glitches and flaws up when working on your second one, if you do choose to do so.