@Aled Edwards
First of all- it would help us help you if you attached a music sheet as well.
I see no need for the piano to double the strings, it feels rather empty especially due to the fact the piano's sound fades away with time.
I like the part starting around two minutes in, but this motive seems to fade away real quickly.
Yey! Dorian!
Melody-wise, I just don't have any sense of continuity but that might be because I don't have the notes to look at.
Also, I feel that you should have used more of the bass instruments (bsn, vlc, cbs...), because it feels as if "we don't have a floor" if you see what I mean.
In general I liked some of the parts but because of the drastic changes in texture and instrumentation it feel more as if you have a few separate chunks on after the other,
as if it was some sort of A B C B A etc etc, which is something I'm not sure you should have, depending on your intentions with the piece.
For example, if it were to be a video game's (looping) soundtrack, although you could have smoothen some of the transitions, I'd get the need for a few different textures.
But
If it's a standalone piece, you might want to reduce the amount of ideas, maybe split it in a half then use the other half for a different piece.
I had this problem at the beginning of my composition years- having my pieces built of connected bricks instead of having them being a wall, if you see what I mean.
You don't have to, of course, but I thought you might want to have that in mind.