Third Person (Omniscient), some First Person (Peripheral)
For the most part, the narrator is omniscient. The narrator gives us detailed insight into all of the characters and tells us their thoughts and feelings. However, the narrator sometimes switches over into the first person, using "I" and directly addressing the reader as "you." These breaks between the third person and the first person voice make for interesting reading. Generally, the first person narrative sections are really generalized discussions of topics like history and religion. The actual narrative of the plot and the characters occurs almost exclusively in the third person, with a few notable exceptions. The very first chapter has the narrator using the first person to describe what seems to be a "memory" of a young Maggie Tulliver. It is never made clear if this is simply Eliot herself or the narrator is supposed to be an actual character who is somehow all-knowing and omniscient.