The P90f is not an aperture grille monitor, it's a stripe pitch. The P95f is an aperture grille. I have a P90f, and actually, I like it quite a bit. The only complaint I think one could make is that it takes a little while to warm up, and until it does it has some geometry issues. I've noticed people complaining about fuzzy imaging in the middle of the screen as well, but I've only noticed this when cranking the refresh rates past what Viewsonic officially supports (their drivers allow for refresh rates beyond what they actually support). Otherwise, it's crisp, bright, high-res imaging all the way.
So, I don't think the P90f is the best monitor I've ever used, but I'm happy with it, I think it'll serve me well until I can afford a 21" or 22" monitor.