See, I like Redwall the best of the series, although it's obvious that he seriously rethought his mythology after it, so that there are a lot of mentions in there that don't make sense with later books. It has a sense of menace that most of the later novels lack -- after Mattimeo (maybe Mariel), at least, the villains get a lot less effective and scary, and I still think Redwall has the best climax of the lot.

I'd say that with the exception of The Bellmaker, it's not worth reading past Salamandastron at the very most, which is where they really start feeling formulaic, iirc. The first 3 published are really different from each other and are probably the best he wrote, but while I'll admit that Mariel isn't as good, I have a soft spot in my heart for it.