Both Mafia games are amazing, the first one especially.
It was developed by some twenty people, most first-time devs under 25 years of age. They had no idea what they were doing, there were no rules and preconceived notions on how to develop, there were no games on the market attempting to do similar things. They developed their own engine with best car physics ever and the kind of graphics that Max Payne was famous for, except they pulled it off in open world. Every level was unique, story was extensive and emotionally impactful, and as a cherry on top there was extreme ride mode with awesome missions like catching speedy gonzales.
Simply put, Mafia is one of the greatest games ever released, and stands the test of time wonderfully.
Mafia 2 had very tumultuous development, they started on their own engine, only to switch to renderware, only to get fucked over when EA bought Criterion and stopped licensing it out.
So they had to build another engine, and to make it more fun, for next gen too.
In the end, the game was still beautiful and atmospheric, but its potential was not fulfilled, many features and story aspects were missing.
Many of 2K Czech devs went to Warhorse Studios to work on RPG Kingdom Come

eliverance, so I do not expect too much from Mafia 3.
But it would be nice if it was faithful proper sequel to first two games.