While the models are definitely higher quality than vanilla, balance overall in vanilla renegade is much better. Most maps in renegade are 50/50 odds for each team winning (other than field). Reborn on the other hand is definitely lobsided in the balance department. Also it needs a serious rework of the repairgun and c4 mechanics as well as more variety in characters. Think of the changes made between Tiberian Dawn and Renegade. Vehicles are also rather useless unless you have a huge rush. There's no convenient way to repair a tank on the battlefield. The mobile repair tank is clunky and requires another person and GDI has to return to base and pay money to repair a tank. Also the lack of the ability to repair nod characters in the field is also a sore point. (other than cyborgs in tib).
What i think would be cool if someone could renegadize tiberian sun, the same way tiberian dawn was tweaked.