She should NOT have had such intimate knowledge of the Falcon or piloting skills given that she was stranded in the desert most of her life. She should NOT have learned how to use the Force so fast. Also, I feel that we are asked as an audience to excuse the fact that she (IMO) takes MORE pleasure in messing with people's minds than Kylo Ren himself. I feel that the writers were too afraid to let her suffer a defeat or make her work for her win; they made Kylo temporarily stupid by not having him cut her right down the instant she started that meditation mess. And finally, I do not feel we saw sufficient evidence of the social or educational deficits and PTSD she should have had from her isolated existence in the desert fending for herself.
Basically I consider her an overpowered Mary Sue.
(As far as Kylo goes...I think the fact that he's still caught between light and dark is why his eyes never change color and why he still looks the way he does.)
I think you may not exactly have an unbiased opinion....
My complaint is her aversion to the force. It wasn't that she didn't believe in it, it wasn't that she just didn't want it, it wasn't even that she was scared of it. It went past all of those into an almost uncontrollable "run screaming the other way" phobia. And then she was ok with it.
I posted elsewhere a long while ago my theory on why she was able to use the Force so well so quickly. Basically, in simple terms, she has a very disciplined, ordered mind. She's had to have ridge self control to survive on Jakku. She's had to learn to control her anger when she's being cheated out of salvage or food, she's had to learn to control her fear when searching derelict, may come crashing down any moment, star ships/vehicles for said salvage. She's been abandoned, so she's had to learn to live with no attachments. All the channels in her mind were alread set and ordered, all she had to do was let the force in.