#1: Is a little empty. The colors are nice, but everything is too horizontal and empty of shape.
#2: Looks like unintentional. I like the contrast of colors from yellow on the sky, but seems to me that the subject is missing focus. Maybe isolate less flowers?
#3: Best of the series. Nice and fresh (I miss spring!!). Maybe a little too busy, but good.
#4: Colors are off, seems way too green. Also, the center of the rocks are blown out from the sun. Not sure what you intended with this
Overall, it's good in my noob's opinion. You should read a little more about composition (for #2) and shapes (for #1).