I am planning to start Gintama, but i have a few questions

Hello everyone, I thank you for taking your time to read and answer this

I knew Gintama from far away as of now, only seing openings/ending/youtube clips from the show.

I know that Gintama is a long-running series as old as One Piece, but I am willing to start and keep up to date this show that I wanted to watch for so long

But first, I have some question regarding this -peculiar- thing called Gintama :

• Is there a real plot ? I moslty know Gintama because of the massive amount of references and parodies to other anime/mangas and the humor of the show, but I read somewhere that it was a story about Edo-era samurais in a modern-day city fighting aliens, and I'm wondering that if there's more to it.

• Obvious question, but : Anime of Manga ? I am planning to watch the anime then keep up with the manga, but is the anime true to the manga (like, every detail in the manga is really in the anime) ?

• From 1 to 10, how good is this show to you and give me 1 reason to watch it as soon as possible (besides the silver balls vs golden crotch thing, because this caught my interest in Gintama further)

Thanks again for your time and answers, and I hope I'll enjoy Gintama as much as you all do.