Excellent, considering it's your first submission.
Congratulations, this is a great movie for someone new to flash (or new to Newgrounds) but there's a few things I've got to point out.
Firstly, your graphics; You picked a good background, and the R.Ms phasing in was a good touch, but Megaman X looked like he was cut out of paper. As for the water, while you used dialog professionally to show that it was water, well, it didn't look like anything at all, just some transparent blue slime, and the shots before that didn't look that good.
On to your style, I thought that the storyline wasn't that hot, but at least you stuffed in tons of funny stuff (8 for humour), and you didn't let it go on and on...
With the sound; good music, but that's all, some voice acting would make the whole flash twice as good (but that's a bit much to ask of a first flash submission).
I hate too much violence, so bloodbaths get a low score from me. You had some plasma shooting around, but that was it, apart from a threat to bash MegamanX up at the end. You still get a good score for Violence, though.
Some users might think I'm silly to give you a 5 for Interactivity, but you get it for having a play button, which is about as much as what most authors have.
I already gave something for your high humour score (check the style), but I'll type some more on it. You had a repeating joke about X being unable to go through a door, and the best (beside the repeater) was the one with X's 'bath'.
I'd like to conclude by typing (Speaking of which, I type too much) that making a sprite movie is probably very hard. I don't know, I've never even USED flash before. So you're probably one of the best first time authors on Newgrounds there is. Keep up the good work!
-From Nexion