I started watching it recently and am about 14 episodes into it. I swear it's the funniest anime I've ever seen, I'm surprised that even the toilet humor comes off fresh (no pun intended...). I thought the lack of arcs would make it rather dull after unrelated episode after unrelated episode, but I was so wrong :3
Gintama is a great anime, I don't remember how many times I laughed so hard. Sometimes it is not funny at all, but some episodes are just great. I like the episodes where they fight about who gets to eat the most food the most. And I really like how sometimes it is really serious.