Well, going on the only three pieces you have up I can honestly say that I don't see any appeal to it, personally. To me it looks like you've used way to many filters and badly pasted in textures. There doesn't really seem to be a style at all, at least not in the three pieces you have up, in my opinion.
They’re not saying YOU are rubbish. They are saying that the few pieces you have posted do not appeal to them.
You have admitted that you devoted minimal time and effort. So imagine what you might do if you devoted more time and effort. Your work is all over the map.
What is your goal and focus?
Work on elements of composition, color balance, blending techniques. Don’t over filter your work either, to compensate for shoddy editing. Spend more time and get a feel for the medium before you give up.