There are too many reviews already to fret over one detail or another, so here's my brief take: my fan is well balanced, no perceptible wobbling or shaking at any speed.  The blades spin freely suggesting little bearing drag to strain the motor.  I found that it easily fits several of my windows without actually mounting it (i.e., installing the four screws that come with it).  That's a plus for me because I may want to use it in different rooms at different times - I can just set it in a window when needed, then remove it when I want it elsewhere or not at all.  My wattage meter says it uses about 63W on low and 78W on medium (very quiet at both low and medium speeds) and about 110W on high (noticeably louder than low/medium but not at all intrusive or annoying in my view).  If my house were bigger I'd buy another.  Good stuff.