"Total War - Rome 2 [Vanilla Plus]" is a small but carefully chosen collection of addons for Rome 2 that improve the game in a vanilla style fashion. Certain aspects such as melee combat are changed (because they are awful in vanilla Rome 2, we all know that), but most changes are not very radical. I see this collection as a sort of "Vanilla Plus"-experience (hence it's name): it improves the campaign experience, but not nearly as drastic as big mods like Divide Et Impera.

I have played hundreds of hours with most of these addons and so far I always had good experiences with them.

Have fun.