The game isn't as bad as most say it is.
There are many weapons in the game you get to choose from but you'll have to buy most of them and there's so many things in the game that you have to unlock like car's and boats and you can buy stuff for you're mansion and so on which is fun to do. So being able to do all that makes selling coke all the more important.
Even though I'm a big fan of Scarface I'll admit that the story was so good that's the only thing about the game that could have been a lot better than it was. But that should make you not want to play the game because this is a fun game. If you don't thank that it's worth buying then you should at least rent it and give it a try.