The vintage Dior Homme is more dense with iris and has a stronger opening and projects better. I would say that the newer version is blended better since it actually lasts a bit longer. If you love Iris then get the vintage, otherwise the reform is perfectly fine.
The DH reform has more cedar. I think they did the same thing with DHI, turned up the cedar and turned down the iris... i dunno why, maybe to 'man' it up a bit? I think it smells a bit cheaper because cedar is kinda skanky and only good in small doses to me. I wouldn't say that the reforms are deal breakers but they are rather disappointing.
I just picked up Dior Homme from Sephora a few months ago, I have not smelled the originals or the intense versions. I do, however, really like it. Not actually sure if I would want more iris in this fragrance, but I can see why some might. It is a well-crafted fragrance that gets many compliments.
I've tested all three formulations of Dior Homme (the original "vintage" version, the first reformulation, and the current version). I own two bottles of the vintage and a big bottle of the current stuff. While it's true you'll notice a difference between the old and new if you pay close attention, the truth is, for any practical purposes, the current formulation is great and quite close to the original. What's the difference, then? The original has a (relatively) bigger blast of iris in the first half hour or so, and the overall scent in development is more subdued. The current version adds a bit more bergamot at the top, and amps up the leather/cacao/vetiver base, making the whole thing more robust and longer-lasting. But really, it's a subtle difference. No one should hesitate to grab the current version; it's good stuff.