I don't agree with Claire btw...
It's a matter of opinion but for me FFX-2 is worth getting although by no means the best FF it's certainly not the worst..
Eh, it all comes down to preference. I found this game to be rather idk..... shitty. Had Yuna not looked like a spazzed out slut bucket and acted like Rikku, and had blitzball been fun like on X then I may have liked this game. If it were me though and I hadn't played X-2, I'd atleast rent it and play it to see if I like it. Half the time whenever people tell me about something and they think it's bad, I wind up thinking the exact opposite.
So if you really wanna play it, I'd rent it 1st.