Dance for String Orchestra and Timpani

This is my first piece for a large ensemble. There are a lot of Octaves and Unisons but I think they work. Do they?

Overall, is it good?

You would need a very strong timpani player for bars 29-30 to do it on four timpani (which is pretty standard). It's doable though - I reckon I could get it. I'm guessing you were more exploring the tone colour potential rather than writing with a real player in mind though.

Musicality wise, there's nothing wrong with the idea you've presented in bar 11. It's fairly static, balanced, and predictable - but, many composers have based pieces around static and predictable melodies. The challenge then becomes doing interesting things with it. It's good that you introduced the syncopation in bar 15, but then in 19 onwards you really need to start playing around a little more. It's not so much that the octaves/unisons don't 'work', but you've had octaves/unisons for 8 bars now, and they get very repetitive very quickly.

Some ideas for what you could do in bar 19: Introduce a countermelody to go with the melody, change the texture (have less instruments, or have them be staccato), or introduce a completely separate second idea (maybe in G minor to have some harmonic variation). Whatever you do, it should feel like it is still 'connected' in some way with the theme even if it is contrasting with it. The change at bar 27, for example, would be too jarring to have at bar 19 because there is absolutely nothing connecting the two ideas - but it would be fine to have if you had already developed and explored the first theme.

Keep writing and experimenting though! The only way anyone gets better at composing is by continually writing, listening, and analyzing, and eventually you get so that these ideas just flow out naturally, the same way a professional chef can improvise a dish because he knows what goes together and what doesn't.