I was pretty excited when they went to 12 team, but ...
Yep, me, too.
Upside is that at least the best 6 or so teams will tend to make it in, even if the others are not the best and thus are in at the expense of better teams.
Causing this, I think, are two big problems. One is conf. champions getting byes and ending up as seeds 1-4. Two of those are usually going to be weak compared to the rest of the field because the Big10 and SEC are by far stronger conferences.
The other problem, even without the conf. championship issue, is that the ranking system sucks because strength of schedule doesn't figure in as strongly as it should. Have Boise State, Arizona State, SMU, Indiana, Notre Dame play the same schedule as South Carolina, Miss State -- or Michigan for that matter (who played #1 Oregon, #2 Ohio State, #3 Texas, #8 Indiana, #22 Illinois) -- and I don't think they'd be in the playoffs.
I really wish they'd just move to an elo ranking system, which automatically takes into account strength of who you play -- no judgement used at all -- then take the 12 top teams, with the top 4 getting byes.
However, it would mean few teams would want to play conf. championships. And since conf. championship games bring in money and are nostalgic, conf. championships won't be gotten rid of. So would have to think about how they can be done in a way that teams want to play those.