I always felt the primals were lacking personality and the story behind them they don't even feel threatening, I think they should have incorporated some big catastrophies into the storyline that the primals cause (bar bahamut). Like with the leviathan storyline you (spoilers) hear that he wiped out a settlement before with a tidal wave but why didn't they include a CG cinematic or something? And when you first see him he just floats away looking so stupid...

I guess what I'm saying is they don't feel threatening. The "threat" they pose is very "this might happen!" Opposed to "Garuda has appeared and has sent a big ass tornado towards Gridania!" Or something...

Shiva looks bad ass, but the storyline will still be "someone spotted a woman who looks like the primal Shiva! She might freeze us all! Go kill her!" While standing around in Coerthas talking to a random NPC....