This sounded like a good and fun idea; lets bring an aging Rocky and Raging Bull together and base an entire movie around this one main premise. Well, it's not quite that simple of course and I unfortunately also have to say that the movie doesn't work out as a very good or even fun one.
One of the big, big mistakes that this movie makes is that it gets turned into a goofy comedy. Now, that's an approach that could have worked out, if only it had the right type of actors for it. Stallone and De Niro can do comedy but they are clearly not the right type of actors for just any kind of comedy. The exaggerated and forced comedy of this movie really doesn't suit their acting style and they were clearly struggling at times. I even have to say that I liked Kevin Hart far better than either Stallone or De Niro in this movie due to the simple fact that he knew how to handle the movie its comedy. Luckily there's also still Alan Arkin who plays a good and fun role but really, this should have been Sylvester Stallone's and Robert De Niro's movie of course but due to the approach of the movie they are never given the opportunity to truly shine or show the viewers that they still got what it takes to carry a 'big' movie.
And really, the comedy itself is quite weak as well. It's because the movie is too simplistic and predictable with just about everything, including the comedy. Old men jokes are getting pretty old anyway, especially nowadays in today's society, when 'old' men over 60 are more vibrant and lively than ever.
But the movie is trying to be more than just a goofy comedy. It's also constantly trying to add in some drama but nothing about the movie its drama ever works out as something good or interesting enough. Again, this is mostly due to the fact that the movie is an incredibly formulaic and precipitable one. Also, all of the drama and dramatic developments were far from anything solidly written and handled really. We are supposed to believe that the Robert De Niro and Sylvester Stallone character hate each others guts, yet the spend the entire movie together, talking and laughing like they are old pals. There is never any real hate between those guys, so when the movie also finally gets to the boxing match, it really isn't anything that exciting or engaging to watch but the same goes for just about anything in the movie; it's never good and engaging enough with anything.
It's of course not the most terrible movie around but it nevertheless remains a pretty bad and disappointing one, especially considering the movie its potential.