After seeing pictures of it, and comments from others complaining about the size, I was initially steered away from the SEL18200. It does look ridiculous in pictures mounted on the slender NEX-5. But in person, it's a different story. The metal build quality is superb, and feels great in hand.
The weight and optical steadshot are just perfect for my preferred shooting method: Left hand supporting the lens, LCD flipped up, and shooting at waist level. For street shooting in good light, the 18-200 range means I don't miss many interesting moments regardless of where I'm standing. Like many super zoom lenses, contrast erodes at max 200mm zoom and colors are a little washed out. Focusing is also slow at the 200mm end.
From my testing in A mode and EXIF, maximum apertures through the zoom range seems approx as follows: 18mm - f3.5 19-26mm - f4 27-37mm - f4.5 38-46mm - f5 47-143mm - f5.6 144-200mm - f6.3
For $800, I would have liked f5.6 at the long end similar to Canon and Nikon's superzooms. But the SEL18200 is absolutely silent and wonderful for video, so I'm just being nitpicky. Overall, this is solid all-in-one solution.