Gintama doesn't have an overarching plot, but at least it doesn't pretend to like most shounen shows such as Bleach, Naruto and DBZ, which all clearly make shit up as they go along and then retcon things in later (though to be fair to DBZ, it doesn't really pretend to either - Toriyama openly admitted he can't write proper stories). Like all other anime comedies I've seen, it can be pretty hit and miss but when it does hit, it's often more than just "OH JAPAN YOU SO CRAZY" like other stuff like Shinobuden and Excel Saga. This may not matter if all your friends are equally geeky but it's always welcome to have an anime that you can watch with all your friends and know they'll all enjoy it - especially a comedy one.
But yeah, as for this episode, it's one of the best I've seen. I love how they reuse the old stock intro footage with the borders on the side. I was thinking "Oh man, I've seen this done before in so many shounen - even the good ones" and then it's all just a parody, Gin gets pissed off that they're using the same old intro and then the borders slide away to make it 16:9. And dat OP, so good.
