How closely the plot mirrored a New Hope. They can't keep upping every thing (this film did not need a superweapon 100 times the size of the Death Star, or a superweapon at all)
How proficient both Rey/Finn were with a lightsaber against Ren
All the unanswered questions regarding the formation of the First Order and why the "Resistance" is such a small group (shouldn't the Republic have some sort of military force)
It was missing some of Lucas' small touches that make Star Wars what it is... While a very good film, it feels like a step-child to the other films given the fact that Lucas was not involved
One observation that is neither good or bad. It is almost as if they had a checklist of everything they needed to be overly politically correct. I wish that wasn't a driving force behind everything in today's culture.
As an 11 year old, I thought Phantom Menace was the greatest thing ever. Without Phantom Menace, I would not be a huge Star Wars fan. The prequels get a lot of hate, but I'm fairly confident that any Star Wars fan in the 20-30 age demographic can attribute it to the prequels... I don't remember any of my 11 year old friends having a problem with the acting, Jar Jar Binks or pod racing. As an adult, I can see a lot of flaws in the prequels that rightfully warranted criticism, but I would argue that the targeted audience for the prequels was not adults. The prequels created a new generation of fans and moved a lot of merchandise.
You could make the same argument for the Clone Wars series. I have never had any interest in watching the cartoon, but recognize I am not the target audience.