For me, I don't like SNOT b/c the tiles are too reflective. They don't have any texture, and so they come off as less realistic when used for flooring, roofing, and anything that in real life doesn't offer you a poor substitute for a mirror.
Now there are times when SNOT is good and the textureless nature of the tiles is welcome, and finding those instances is the challenge. I think one of the biggest challenges to SNOT style that I've seen is trying to do it in such a way that there is enough happening that you don't notice the glare that the tiles produce. Take Aliencat's Reality Dysfunction
. Even though his street is SNOT and you can see the reflection in what shouldn't be reflective, there is so much going on that unless you are looking for it, you don't see it.
At the same time, I've seen MOCs where they SNOT'd, and there just isn't enough happening to move your eyes away from the fact that the pig sty looks so sterile you wouldn't mind having major surgery right there on the floor next to the food trough. From looking at it, it is clear that they shouldn't have SNOT'd, but left the studs to add some realism to the scene.
I personally only use tiles where the studs actually get in the way of something(a sliding door, landing pad, etc). More often then not, it's b/c I have something moving and need the tiles so I can support it's movement.