I don't usually like classics (just personal preference), but this is such a good series. Definitely top 10. Pros:
-If you read the books individually, they are pretty easy to get through since they aren't very thick.
-The world building is insane! So good, and to think that this came before all the wonderful modern day fantasies. His imagination must've been insane.
-The covers on some of the editions are beautiful
-One of my favorite narrator voices of all time
-The characters are relatable and (I think) well constructed
-The different books are tied in together very well even though they have different characters
-I didn't notice any plot holes / things that didn't make sense
-I really liked that when I was reading books further than the first one I would go "Oh I recognize that!" or "That makes sense!" and such reactions about how the books referenced each other.
Cons:
-The first, third, and fifth are a bit slower paced.
-If you don't pay attention (especially in the latter books) it can be quite confusing
-I can't think of any more except not very diverse, but it is an older book by an English author so that is understandable