On one hand, it is interesting to play through the games that started the entire series. You get a sense of how far the games have come since their early days, with all the features that have been added or changed.
On the other hand, I won't lie to you. Red/Blue/Yellow are very rough games to get through if you are spoiled by the updated features of the later games. R/B/Y have glitches, weird bugs, and odd things that can frustrate a player. You'll find moves missing that should hit. You'll find that you can't carry as many items as you want, and your bag is going to become really disorganized. Even the box system is primitive, where you can't easily move your Pokemon around. And you always have to remember how many Pokemon are in a box before you go out and catch a new Pokemon; you can't catch a Pokemon if the box you're currently on is full.
The game is still a lot of fun, though! But I'm saying that as someone who started with R/B/Y and is used to the old games. Since you never played the original, you should really decide if you want to see where the series got its start, and if that is a good enough reason to go primitive again.
