I have used several sets of the MBUS sights over the years. In general I prefer the Troy better, but I still have a couple of uppers with the Magpul MBUS on them.
First, the Gen 2 sights are an improvement over the Gen 1. The rear flip aperture was really poorly thought out on the Gen 1. And the adjustments seem to work a little better on Gen 2.
Second, my only complaint about the MBUS is the front sight post. All of the ones I have configured on my rifles, and helping a couple of friends at the range were configured so that the front sight post is way too low. As a result, you end up threading the front post quite a long way UP, with the adjustment plate creating this sort of + shape instead of just the front post when you look down the rifle. You don't see the horizontal part once you look through rear sight. When you get into the rear sight and try to get a sight picture, it has the effect of putting the post top HIGHER into the wings of the front sight than I have seen on any other sights. It works just fine, but looks odd compared to traditional front AR sight. I suspect they could have designed it with a taller post, or higher "wings" and enclosed the adjustment plate.
I found this photo on the internet, these posts are higher than on any of my uppers, but it will give you the idea...
Final comment - this is convenient/annoying all in one. The spring loaded deployment of the sights is very convenient and fast, with a solid stop point. Definitely easier to deploy than something like the Troy with the stiff detent button. However, that also means that you'll bump it from time to time and deploy the sight unintentionally. Usually it happens to me when I am messing with a rear scope cap, taking it out of a case, lowering out of deer stand, etc.
