Overall, a very solid effort. I like that there's some variety in style, with the Fall and Summer themes being in different genres. The winter track sort of reminds me of some Super Castlevania 4 themes, which is very nice, and contrtibuted to it being my favourite track out of the set.
The only flaws I can hear is that some tracks end quite abruptly with the fade-out. They could've looped a bit without getting repetitive. But speaking of repetition, some tracks do have a little bit of repetition here and there that can get a little tiresome, such as Spring. It's still a great track, but on repeated listens it could grate a little. Also, some of the instruments sound a bit lo-fi.
All in all, a very solid set of songs that I've definitely enjoyed!