What do I see in my old writing?

I recently came across some things that I had written when I was younger. I was probably in my late teens or early twenties when I wrote them, and I couldn't help seeing how much I'd grown as a writer. I notice the early flaws that I made, for example, I never thought my plot through, and there were often grammar and spelling errors throughout, but my characters were well thought out. The story line that was there could be usable in future works.