When you return to a place after a gap of years it can seem smaller and far more ordinary than how you remembered it. The same applies to re-reading books. The imaginative tale you remembered can now seem derivative, the creative prose clichéd. It's disappointing, and might deter you from revisiting these old 'friends', however there is an upside. Books that you once found incomprehensible or uninteresting might now reward you if you read them again.  When I first read 'Ping' by Samuel Beckett I couldn't be bothered to try to fathom it. Years later, I tried it again–in fact, I wrote an assignment about it for my MA. I now find it haunting and incredibly skilful.
Taking another look at things you wrote some while ago can be risky. Maybe a story you used to be proud of will now seem stilted or stereotypical. Perhaps it was rejected in the past and you couldn't understand why. Now you might be able to see how to improve it. On the other hand, you might find that a piece of work that you once dismissed as worthless isn't that bad after all, and with a little work it could find a publisher.
Of course, it isn't the work that changes, but the person reading it. If time has altered your point of view, it proves that you've grown.