Good, but should be expanded
What you have is a pretty good accompaniment, in my opinion. I would suggest that you add more of a tune than what is taken by the bass in this extract, for example, on the violin. Think along the lines of the moonlight sonata; nothing complex, but something to add a bit of variety. Also, if you wish to bring the percussion in, give them a longer fill as an introduction, as the "unexpected" entrance doesn't work so well, in my opinion. The ending is a little abrupt, though you could use the chord progression that you have and just add a broken A minor chord with a roll on the ride cymbal.
As I usually say, don't give up on the piece, but develop it and post your results.