Middlemarch is a finely observed, keenly realistic, deeply psychological picture of provincial life in the early 1830s. It is extraordinarily accurate in its dating given that it was written in the 1860s, and it glances with humour and sympathy at each social class.
It's also sensationally dull.
For one thing, it's long. Most editions run to about 700 pages (not this one, but this one has big pages and a small font) and 86 chapters. This is not, in itself, an issue: The Dark Tower, one of my favourite books ever, contains (according to Amazon, although I'm not sure this can be right) over 1000 pages. It's just that Eliot tells us every single inconsequential detail about a character's history and motivations and everything they've ever read and everything they ever said and oh God I want to kill myself it's so dull. I just could not bring myself to care about Dorothea's stupid marriage to dry old Casaubon (serves her right) or Rosamond's selfishness or Featherstone's bloody will. In fact, if I hadn't had to read this for an essay, it may well have made me break my rule about always finishing a book. That has only happened once in my entire life. That should tell you something about how boring Middlemarch is. Sure, there's a lot you can write about in it, but that's not why you read a novel. You read a novel to be entertained, and this just doesn't do that.
(In the interests of being completely fair, I would like to add that I did feel genuinely sorry for Fred Vincy when he defaulted on his debt, and genuinely happy for Dorothea at the end. But two moments of maybe two pages each in a 700-page novel is not enough to justify another star.)