That's my biggest issue with Rey's backstory or origin is the very fact that it turns out she isn't special at all - she's not from a Jedi bloodline or royalty - she's just a desert dweller with hardly any past, yet she can use the force and use it way too well for someone who just got thrown into the midst of a hundreds-year long regime war. Using that logic, FINN could be a damn Jedi. ANYONE can be a jedi. You don't need experience or training and it doesn't matter who you are or who you're related to. That's altering the lore of what SW had set up previously only to make an exception for the new lead character. She's not special (and she doesn't have to be special in the sense that she needs to be a princess or "the chosen one") she's just as much of a normie as all the other side characters. It doesn't make sense with how Star Wars had always been written.
I would accept Rey as a good character if they actually showed her learning to do amazing shit. But they never explained or showed her LEARNING anything. She just does it willy nilly and we are expected to believe that she just can? How can she speak wookie? How could she re-wire and fly the Milennium Falcon? Why did Luke's light saber call to HER of all people? It's never explored. She bested Kylo Ren in battle (even Finn couldn't defeat him when Kylo was injured..Finn, who is already a trained storm trooper and probably has more combat experience than Rey), she bested Luke on the island and could have killed him, she killed a few of those red soldier guys that worked for Snoke without but a scratch on her arm. How? It's lazy.
Luke started as a Rebel fighter and flew a ship to destroy the Death Star, not using a light saber. He learned that in the second movie. He had a full movie of learning. He started as a naive, whiney farm boy, joined the Rebels, learned the Force, faced his father, failed, but ultimately came out on top a stronger person than he was at the start of his 3-part arc.
If they fixed some of the things people complain about, I wouldn't doubt for a second that Rey would be a great lead. She has the gumption, the attitude, the charm to do it.