The General Prologue isn't much more than a collection of character descriptions but they are incredibly skilful and, beautifully presented. They have levels - the realistic, the satirical and the allegorical and they challege what you think about them. The writing is gorgeous. It doesn't try to make you think, it doesn't force you with an opinion, in fact it provides basically no opinion at all, and at the same time it's written well enough to get you thinking exactly what Chaucer wants you to think.
The language is old and obscure, but in a way it makes it more exciting to read, as you're having to translate as you go. It's like finding some ancient scroll, or an alien code, and creates an even deeper sense of a little world in a drop of water. I remember reading Shakespeare at school and there was this sort of unspoken assumption that the language would be a barrier, a hurdle to try and get over. I think that particular attitude misses a trick. The language does make it difficult to read like an ordinary book, but it makes it more exciting to explore.
In Chaucer particularly the fact it's written in Middle English makes it all the more exciting when you find a sentence that you can easily translate. After a while you start reading the words with strange pronunciations and saying 'eek' instead of 'also' in general conversation. It's like a foreign language, but it's your foreign language, and you can see how words and phrases have evolved over time into modern English. In Chaucer's time there are sayings, and memes, and stylistic conventions that you can see reflected over time.
It's history and literature all mixed up together by an incredibly talented writer. A little snapshot of a strange world which is oddly familiar.