the song has a really painful chord wich is that weird G
Flute is painful, change it to something else
the super presence of the low tom is painful
There are some (not a lot) notes in the lead that are painful

Awsome build up
Awsome boom
The punky part is generic but the chords had chemistry, which is important
Lead was good

C4C check out the one in my sig
Just had a listen myself and for a first song it's not that bad, however:

Some chords certainly need looking at (like the G said above).
Take out or reduce the use of the mid tom on the drums as it seems too harsh, you could keep it but make a less brutal, boring rhythm . The same applies for the hi-hat (and add a snare!).
I toyed around with the flute(s) and to be honest it sounds so much better as a hammond organ - which would also help add to that pop-punky feel you seem to have going.

Clean up the chords, make sure your lead stays in key (perhaps a few notes out of key, I could be wrong) and make sure you change those drums but it wasn't a bad start .