I've been thinking a bit.
As Cullen is now a confirmed LI in the game, are you going to be romancing him on your first playthrough? I remember playing DAO for the first time as an elf and discovering just before the landsmeet that making Alistair the king without having hardened him would make him break up with you. Took me completely by surprise as I had not been spoiled on it until then. Such plot twist are great but have a way of messing with your plans
Are you going to try and avoid any possible twists with the Cullen romance by playing the game once before romancing him to see what his role is?
I personally am a little on the fence about it. On one hand I like to plan how I'm going to play a game but on the other I loved the twist on the Alistair romance as well as the whole Dark Ritual thing with Morrigan so I would hate to miss out on the surprise! 
IDK. I went into DAO completely unspoiled. My first playthrough was f!Cousland, and she never hardened Alistair, and believed him when he said that he didn't want to be king. She made Anora queen and remained in the Wardens with Alistair. Then I heard that it was possible to become queen if you were in a romance with Alistair (I never said my information was 100% accurate), so I made another Cousland, and became queen, but she never hardened him, so he wasn't very happy about it. By this point, I was getting sick of rolling warriors, so I decideed to try again with a mage. I had no idea how all that worked, and I thought it would be really ironic for Ferelden to have a mage queen, so my next playthrough, she hardened Alistair... and he tried to dump her. Well, she wasn't having any of that, so she talked im into letting her stay on as his mistress. Hey, she's a mage. She didn't give a rat's patootie what the chantry (or anybody else) had to say about the sanctity of marriage. If whoever Alistair was eventually pressured into marrying didn't like it, tough.
When DA2 came out, I spoiled myself rotten. It was a much more satisfying experience.
So yeah, I'm going to spoil myself for Inquisition.