Technically, you're not as far into P2 as you think you are, but if it isn't grabbing you, then there really isn't much to say really. This entry may not be your deal, and Persona (MegaTen in general) is more dungeon crawler than most JRPGs are, so if you're hating the dungeons, you may just want to stop because they are not going to get better for you, especially if the plot isn't doing anything for you to keep moving forward.

If you want to finish it, then go for it, but I would say it may be best to not force yourself to keep lunging through something you are not really enjoying. I had a similar issue with Valkyria Chronicles, just couldn't get into it, and I feel the harder I kept pushing myself to move forward in hopes of finding something to like, the more I began it dislike it.