As far as being repetitive, depends. You don't do the minigames anymore (only 3, and they're all different), but you still have Chase, Battle and Hide-n-Seek with the Pokemon to befriend them, which is more or less the same as in the original.
The main game is still running around, talking, doing a puzzle (like talking to someone, befriending someone or carrying something) and stuff, but there are some new things. Some things involve battles with interesting rules. For example, I had to fight Sawk and Throh, but you need to beat Sawk specifically, while Throh is in your way. And there are fights where a bunch of smaller Pokemon are in the way while you attack a stronger one. Or in one instance, attack a cake. Or run through a hoard of Pokemon to get to the boss or whatever.
And there are the sidescrolling parts, though not many and they're short.
Also consider that you can play Oshawott (who can swim) and Snivy (who can double jump) which adds some variety if nothing else.
But if you didn't like the original, probably not going to really enjoy the 2nd one.
I liked both because they felt like N64 Pokemon games I never got, but always wanted.