I am on my fourth acrylic tank. I prefer them as there is no rim to close off the rectangle so the tank looks more integrated with the room. Acrylic is clearer than glass and looks much better when lights are off than glass too. I flinch when the step stool bumps the acrylic tank but much less than when it hit the glass tank. Acrylic is much lighter as well. The 100 gallon glass tank weighed a lot more than the 180 gallon long acrylic tank.
The only one that was new left here with no scratches but the used tanks were a mess. I polished the inside of the one I have now and was quite surprised that it wasn't that bad to polish. Maybe an hour per grit for a 180 gallon tank then a couple hours for polishing twice?
Acrylic seams will burst. There are plenty of horror stories on the reef forums about poorly made tanks. They can be repaired a bit easier than glass though.
I did scratch my glass tank however. Front and center. Twice. Glass scratches are a bit scary as that is how glass is cut, scratch and break - right?