In my first playthrough of Silver I left him in my box to rot.
In Crystal, I used him for a little while.
In my recent playthrough of Silver, I used him till the end, although I stopped playing after I beat Red. (this playthrough was on an Emulator, not gameboy like my other games)
In Soul Silver, I used him till I beat the Elite 4, but I gave up on him after cause he didn't have thrash or any good moves that he had in Silver like Dragonbreath (well, taught from the TM) or Thrash. So I got bored of him. I probably would've liked him wayyy more if the "Follow me" sprite was larger, he doesn't seem that cool in his sprite. I would've loved to see a regular-sized Gyarados, though that's probably impossible.