Personally I found it rather uninspired. The harmonic sequence you are using is very basic and repetitive. Try to branch out and try something other than a i-iv type motion in the harmony. For instance, you start in a minor, then move to iv (d minor), then to VII (G major) which can be thought of as the 4th degree of d, and then up again to III (C major) which again can be thought of as degree 4 of G. You are basically building a big musical sequence around the circle of fifths, which cannot stand on its own. Sequence can be a useful device in places, but in my opinion it can't sustain a whole piece.
Try to work in a little more melodic content as well. There didn't seem to be much melody to speak of, it just seemed like you were noodling around with a chord progression. There were some parts around the middle that sounded like they could be used as a melodic cell, but you didn't do anything with them. To be painfully blunt, you really don't have anything of melodic or harmonic interest.
Try to work in some dissonance to your music as well. It is very consonant, too much so in my opinion. Adding a little dissonance in will provide some contrast, and add some necessary tension-release which will help to maintain interest.
As for recommendations, it depends on what you want to do with your music. If you are serious and want to try to write interesting "concert" music, then I would recommend you listen to lots of music, of all styles. In particular I'd recommend music from the late romantic period forward, and when I say forward, don't skimp on Impressionist and 20th century music. Try to make a conscious effort to listen and understand why these pieces interest us. Do some analysis to see what the composer is doing harmonically. Try to see how other composers have provided melodic/harmonic interest to their music. As a very basic, though demonstrative, example - there's a discussion of Beethoven's motivic development in the Pianist Corner board. That might give you some pointers for how Beethoven was able to take a theme and use it in different ways to provide unity. That's just scratching the surface, but its a start - again, listen listen listen...
A good effort, but really quite basic and needs some work...
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What you are is an accident of birth. What I am, I am through my own efforts. There have been a thousand princes and there will be a thousand more. There is one Beethoven.