I've always wondered how people that have only played the newer games feel once they play the Gen I games. I started off with Gen I and have mostly played through that game, so it's near and dear to me.
As for if you should play Red or Blue, I'd say yes. Honestly, Yellow version is my least favorite of the Gen I games and I've only played through my Yellow version once. Pikachu is a horrible starter because it limits you so much since you'll only have the ability to catch normal and bug type pokemon before Brock. In Red and Blue you can pick a starter that gives you a varied type, with the ability to catch a Pikachu in Viridian Forest (the forest before Brock).
So if you do continue with Yellow, I would definitely say play through Red or Blue at one point. They are incredibly different games, but I think they are different enough to make it worth the second play through.