No, Darwin cannot be considered to have been mislead by his finches. While I realize that Darwin does have many detractors (most of them Bible-thumpers), his research and all of his other work is sound. It has been proven by the test of time and even other scientific research since then.
Darwin was first truly set on the brilliant path towards forming the theory of evolution (which happened to also be theorized, concurrently, by Alfred Wallace) in the Galapagos Islands, due to the finches. Having highly localized sub-populations with clear needs for different physiological characteristics was far too unlikely to be a coincidence.
I do not believe Darwin was misled by the finches he observed and documented. After all of these years we've come to the point that the theory of evolution is sound and predictable. Darwin's observations covered different species, but he was able to denote several similarities and differences between these birds.
Charles Darwin found finches on an island and used them to help craft his theory of evolution. He believed each bird originated from one finch and then evolved to meet certain needs or ends. Of course, these birds are only found on that particular island, but his finches didn't mislead him.
Charles Darwin wasn't misled by his finches that showed adaptation with different beaks. If anything, just like Sir Isaac Newton's falling apple, Darwin's finches enlightened him to how seemingly similar animals can adapt to their environment. Alligators and crocodiles are perfect examples. They are very similar, yet one species lives in the New World while the other lives in Africa and Asia. Both are fearsome predators. Some live in fresh water while others live in salt water. Both gators and crocs have adapted to their environs to perfection as they are top-of-the-heap predators that have survived for dozens of millions of years. Darwin's finches were a microcosm of the macrocosm in the animal kingdom--Darwin figured ALL animals, not just finches, adapted to what they needed within their own ecosystems.