A mess of Japanese culture and anime parodies, dumb jokes and doesn't get going till the 50th episode. And even then they manage to make it a dumb joke. I wouldn't
recommend it to anyone. Avoid.
Until you watched every other interesting anime show. When you'll have nothing else to watch. Gintama parodies seinen, and manga/anime as a whole, by creating the ultimate one. It's a mix of some of the best-written characters and stories; silly, dumb, and absolutely hilarious comedy; brutal and bloody action; and a hell of an emotional rollercoaster joyride. It'll get you one way or another.
Recently tried to rewatch it. And, well... You need to watch the whole Gintama. This is a crucial step before watching Gintama. Without it, you'll get only half of the Gintama experience.