Looks nice
This sleek, unobtrusive 6.6 gallon looks very nice, very classy. I've had mine about 2 months. My Betta loves his home and the filter isn't too strong for him. My only concern is possible leakage at the top and bottom. I know leakage can occur at the top because I've seen it. There is a detachable black, plastic rim around the upper edge. If the tank is full of water, and you press against the acrylic just below the rim, water will drip out between the rim and the acrylic and run down the front of the tank. Ok, so don't push on it, but still.
The black plastic rim on the bottom is similar, but it appears to be attached and maybe sealed. However, I get some strange build-up on the edge of the rim where it meets the acrylic. I really can't determine what it is, but it isn't hard water build up, it wipes away too easily. I can't press on it and make it drip like the top piece, but I'm still not sure what's going on with the white stuff.
Give this eye-catching tank a chance, just keep your receipt until you're sure. It really will fit on a bookcase, but if you do place it on a shelf you'll never be able to get to the top of the tank when it's full of water well enough for maintenance and cleaning. Mine is on the very top of a sturdy bookcase and looks great.