1. Good use of descriptive language. Use of accents makes each race/species easily identifiable and fun to read. Food Porn and Scenery Porn is usually good.
2. Fight scenes are usually fast-paced and fun to read, particularly in scenes with open warfare where armies are pitted against each other.
3. You can begin with any book and understand what's going on without prior context.
Bad points:
1. Lack of continuity. Many locations aren't mentioned again if they aren't plot-important, even if they're within walking distance of Redwall. Many characters aren't mentioned again, even in books that are direct sequels. The books being written anachronistically also results in inconsistent details.
2. Characters are flat and static. Many are so similar, to the point of being the same character under a different name and setting, due to repeated use of the same archetypes. Any character development that does happen is either only informed or extremely abrupt. The earlier books (1980-1990's) are better at avoiding this.
3. The plots are very simple, black-and-white and formulaic. There are clear good guys and bad guys, and you always have the heroes' main plot and multiple subplots. Sometimes the subplots are more interesting than the main plot, due to featuring more likable characters and/or being more relevant/interesting.
4. The multiple plot threads can also lead to bad pacing or a lack of focus. Loads and Loads of Characters doesn't help.
5. Lack of world-building, coupled with the lack of continuity, leads to a lot of Fridge Logic on how things work, especially if you think of multiple books collectively. For example, where does Salamandastron get its constant supply of metal? How does Redwall never suffer from overpopulation?
6. Villains are usually killed off anticlimactically, either in a Curb-Stomp Battle or an Ironic Death indirectly caused by the heroes. Most of the time we don't even get a cool duel between the protagonist and antagonist. Which is a pity, since many of them are built up as such evil monsters.
7. Aesops and messages can be mixed and inconsistent.
Conclusion
All in all, the Redwall series has a lot of flaws but can still be enjoyable to read. I think it's better suited for its target audience (children) because of its simple story, and its more advanced writing style and use of obscure words is good for kids honing their reading skills. Even so, there are some books that are just really badly written and uninteresting to read (a lot of the books released in the 2000's).
But if you just take them as children's stories about animals going on adventures, it's not bad. Just don't think about it too hard and avoid the later books.
Don't Think too Hard About it
Good points:
1. Good use of descriptive language. Use of accents makes each race/species easily identifiable and fun to read. Food Porn and Scenery Porn is usually good.
2. Fight scenes are usually fast-paced and fun to read, particularly in scenes with open warfare where armies are pitted against each other.
3. You can begin with any book and understand what's going on without prior context.
Bad points:
1. Lack of continuity. Many locations aren't mentioned again if they aren't plot-important, even if they're within walking distance of Redwall. Many characters aren't mentioned again, even in books that are direct sequels. The books being written anachronistically also results in inconsistent details.
2. Characters are flat and static. Many are so similar, to the point of being the same character under a different name and setting, due to repeated use of the same archetypes. Any character development that does happen is either only informed or extremely abrupt. The earlier books (1980-1990's) are better at avoiding this.
3. The plots are very simple, black-and-white and formulaic. There are clear good guys and bad guys, and you always have the heroes' main plot and multiple subplots. Sometimes the subplots are more interesting than the main plot, due to featuring more likable characters and/or being more relevant/interesting.
4. The multiple plot threads can also lead to bad pacing or a lack of focus. Loads and Loads of Characters doesn't help.
5. Lack of world-building, coupled with the lack of continuity, leads to a lot of Fridge Logic on how things work, especially if you think of multiple books collectively. For example, where does Salamandastron get its constant supply of metal? How does Redwall never suffer from overpopulation?
6. Villains are usually killed off anticlimactically, either in a Curb-Stomp Battle or an Ironic Death indirectly caused by the heroes. Most of the time we don't even get a cool duel between the protagonist and antagonist. Which is a pity, since many of them are built up as such evil monsters.
7. Aesops and messages can be mixed and inconsistent.
Conclusion
All in all, the Redwall series has a lot of flaws but can still be enjoyable to read. I think it's better suited for its target audience (children) because of its simple story, and its more advanced writing style and use of obscure words is good for kids honing their reading skills. Even so, there are some books that are just really badly written and uninteresting to read (a lot of the books released in the 2000's).
But if you just take them as children's stories about animals going on adventures, it's not bad. Just don't think about it too hard and avoid the later books.