Here's the nicest thing I have to say about Ivanhoe: there are some good parts. There's some lovely description (mostly in the first few chapters), and there are a few lines that are genuinely funny. And the things I didn't like are aspects I'm probably judging anachronistically.
That said . . .


I was not impressed by Ivanhoe. The character Ivanhoe is nothing to write home about. He's less interesting and just plain does less than most of the other characters. Not that the other characters are great, either. The worst part of Ivanhoe is how Sir Walter Scott chose to write Jewish characters. He goes on and on about the plight of Jews in the Middle Ages, and how terrible and violent the bigotry against them was. And then he'll tack on, "Oh, and all this oppression surely exaggerated their natural, intrinsic cowardice and greed." And then the reader shakes her head sadly. I know I'm being anachronistic. I know it was the 1820s. But the character Isaac the Jew, possibly the person with which we spend the most time over the course of the novel, is a gross cartoon and it's really distasteful to read.
The structure is also challenging for the modern reader. Tangents, tangents, and more tangents. They get more frequent (and plot developments get stupider--no, seriously, there's a footnote where Scott apologizes for his dumbest one) as the book goes along, leading me to suspect even the author got kind of bored.
At least Robin Hood is in it, though. I guess that's something.