i have a 5g hex thats acrylic, and its been just fine for 3 years now. i scratched it a couple times getting rough cleaning it but really being smart about it isnt a big deal.
they make acrylic tanks in all shapes and sizes, not just bow fronts and waves. my girlys uncle has a 40 something gallon bow front that leaked... but im sure thats not the norm, and really glass is cheap.
glass is cheap, easy to clean, resealable/rebuildable, and did i mention cheap? hell with all the money ive saved buying glass instead of acrylic i could get me a house keeper. not really. :P