After I finished 10-2 I liked 10 more (like someone else said, seeing the drop in quality in the sequel made me appreciate the original more), but the poignancy of its (10's) ending was kind of ruined for me because I knew it wasn't the REAL ending to Tidus'/Yuna's story >_<.

But yeah, I think you should just try it. Some people really like it, some obviously really hate it, I'm in between. I thought the first chapter was painful to get through, but the game got pretty interesting (imo) after that. And getting 100% completion is definitely not worth the effort, so just do the missions that sound fun to you (besides those you have to do) and find the Perfect Ending on YouTube or something