Its intresting.
The more you play it the more depth there is. Its a kind of fun metroidvania style game. Lot of nice features.
I am not sure the mario stuff helps or hurts it-when i first played it i thought it should play like super mario-which it doesn't at all.
in that sense its like super mario 2-however supermario 2 had the advantage you just spent 50 dollars for the game so you better give it a shot.
In internet flash if something doesn't catch you in 30 seconds people are apt to go away. If you don't get them in the 30 seconds your going to see a lot of comments like above-which i understand, if i don't agree with.
I realize that this is probabbly what your going for- and what the original metroid is famous for. However a little more guided hand might help it out.
my advice:
Make the enemies a little less deadly. 1 hit death seems a little extreme-in a wow i just jumped on this goomba-wait i am dead kind of way.
Make it so you don't start at the beggining at the start of the levels. that seems a little extreme.
Small thing-don't make it so you have to use the mouse when you start over. i don't like mouse and keyboard with a platformer as it doesn't make a lot of sense.