Acrylic vs. glass
There's pros and cons to each one.... Acrylic is lighter and easier to handle, but it does scratch really easily. It does cost more, but it does have the advantage (for those of us with kids/pets/clumsy husbands) of being practically unbreakable and some are seamless, which eliminates leaks.
Glass is generally easier to clean, cheaper, doesn't scratch up nearly as badly (it takes a razor blade or really sharp gravel to do much to it), and provides a "truer" picture of the size and shape of your fish (due to the fact that it doesn't bow out like acrylic can...). Disadvantages: it's REALLY heavy, usually has seams, and anywhere there's a sealed seam there is the off chance of leakage, and it's easy to break. Bumping into the corner is all it takes for some (although this is normally a problem only if you have a big tank because the glass will torque easier if it's bigger).
Even with the issue of being delicate, I still choose glass over acrylic, mainly for looks. I keep a sand-bottom tank, and a sandblasted acrylic tank would be a terrible thing.... glass is a little more durable for my situation, anyway.
It's a personal preference thing, though.