Ok overall the was quite a good film but it is not a classic like the first Gladiator film was. I'll start off with the bad which is really only that there is loads of poor quality CGI. There is a part where the gladiators are fighting baboons or monkeys that have been made from CGI and they look cartoon like. The first Gladiator film did have a small amount of CGI when the tiger pounced on Maximus but it was only a small amount and looked quite realistic. The thing is over 20 years down the line and the CGI certainly does not seem to be any better or any more realistic looking. In the new film there is actually a short clip of a CGI tiger but it is not any better than the one in the first film.
It is fact that the Romans did not have sharks swimming around the Colosseum, although there were occasions when it was filled with water so that they could stage sea battles with scaled down ships. The CGI of the second of the twin emperors being beheaded also looks cartoon like.
Now for the good. The story line fits very well with the first film and is quite interesting. The combat scenes in the Colosseum were at times extremely unfair odds on the Gladiators which is also realistic. The choice of actors representing the good and bad characters was also realistic and appropriate. Very entertaining and full of action so I will give this 4 out of 5 starts with mostly only the amount of cartoon like CGI for why it does not get 5.