Review of Gintama
Gintama is not an anime for anyone. Coming into gintama you should have prepared yourself with no expectations (you never know what you would get!) You should have the patience and determination to complete a 300+ episode anime already. And you should have a decent sense of humor to begin with. Anyone would tell you the first 20-50 episodes are rather slow and that it improves later on. That is a fact founded upon the opinion of the majority. Outliers always exist, but don't expect yourself to be one. Gintama is a comedy primarily, if you are going to watch it, you're going in prepared for thecomedy. If you're just going to wait for serious arcs to pop up, then you're better off watching something else.
That said, if you DO manage to finish the 300 episodes - or heck, 150 episodes - I can almost guarantee it will be one of the best experiences you've ever had. That is why there are only two types of people when it comes to Gintama: people who dropped it early on, and people who finished it and enjoyed it completely.