Being quite a physics enthusiast I'm up to date with this kind of stuff. No I don't believe in any doomsday scenario, I think the worst thing that could happen is an electromagnet quenching and overheating til it goes boom. I'm not expecting that in today's experiment but rather sometime this year. It's cause I've been following its development and have seen a number of scatterbrain decisions.
I am very interested in if they will see a Higgs boson or not, the nature of mass has been personally puzzling me for some time and I hope some answers come out. I also hope they are able to produce and observe a micro black hole, this would be the first ever account of being able to prove that at least some of string theory is true and that it hasn't all been speculation. If such a hole is created then I'm sure nature has been doing it for billions of years without any danger. I know the mass threshold a black hole needs to have in order to self-sustain, it's about if you took the sun and crunched it to the size of a bowling ball or the earth to the size of a pingpong. They need a certain gravitational intensity in a certain space so that the escape velocity becomes greater than light. It needs astronomical amounts of matter and even more such power to FORCE that matter to become a stable black hole, colliding two protons is billions of billions of billions of times less than the minimum matter required it's just not gonna happen, whatever BH is created will spit out its energy much faster than it could swallow and evaporate, the bottom line is that BHs don't come in just one size as the dreaded world eaters they've been known for, it's just that nature only allows creation at that scale. They could, if this experiment turns right, also be created in labs where they are much more harmless and frail.
As for the LHC itself, leave it to the Americans to screw up on both costs and elaboration. Upping costs to 3x the original cost is one thing, but I hate how they turned a top-notch scientifical project into an international manhood-measuring contest, swinging between calling it an international project and their own, demanding credit yet begging for money, at least I'm glad they finally reached a sort of consensus. I just hope there won't be the same amount of babylonism when it comes to interpreting the results, which is sadly too much to ask for.
And yes it DOES look like a Stargate.