I own one. The quality is OK.
Keep a tube of silicone and a caulk gun around just incase things go bad. I've never had any problems. My original 55gal a friend of my parents now has, has about 3 years on it and it is still going fine.
THOROUGHLY inspect it for scratches on the two long sides. Take a flashlight with you. If you ever go reef glass scratches stick out very bad. Once it leaves the store you're SOL. Don't buy it if it has any scratches in it.
The seams/seals are ok, they're not on par with the quality of an oceanic for example, but you're paying a lot less.
As far as overflow box, let's say you had a sump with 30gallons capacity. If the power went out while you were at work/school, whatever and came back on you could be looking at 30gallons of water on your floor if you overflow box doesn't work. The cpr is much better than anything else I've seen.
WARNING-the few SW tanks where you are going are bunk. Order from SWF.com and you'll have much better luck plus help support the board. He doesn't acclimate his fish if you're going where I think you are, he just dumps them in .
