Good piece of 'kit'

I got this lens for free with the X-E1 and overall I would say it offers excellent value.

The build quality is generally very good, the lens is quite solid without being excessively front heavy. The zoom action is very smooth; unfortunately the same can't be said for the manual focus ring which has a dreadful throw. The aperture ring is a bit loose and can be turned by accident: for this reason I always turn the camera off when it goes in my bag.

Image quality is fairly consistent across most focal lengths, the sweet spot is around f/5.6 which makes for ideal walkaround snaps. It's less proficient at landscapes where you want critical edge-to-edge sharpness: the corners never really sharpen up as there's a fairly hefty barrel distortion being corrected for at 18mm. 35mm has very good centre sharpness, while 23mm has very consistent edge sharpness. 55mm is capable of producing a very pleasant blur at f/4, but the centre sharpness wide open at this focal length isn't amazing, so it's at best a poor-mans portrait lens. There are some annoying chromatic aberrations in the upper right corner at 18mm.

Autofocus in bright light is generally good. In dimmer light, it tends to average out at around a second and in dark conditions it hunts a lot more. The fastest is definitely the 18mm end, whereas the 55 can be quite slow. With C-AF it can produce some acceptable tracking shots but the keep rate is probably not high enough to be a good wildlife/pet/hyper children tracker. As previously mentioned, manual focusing is painful.

One of the best features of the lens is the stabilization: at 18mm with stabilization turned on you can get sharp images as low as 1/8 of a second. I recommend turning it off at any speed over 1/250 as in some instances you can get ghost blurring.

This was my main lens on my recent trip to South America. It just has that little bit extra than a standard kit lens, being both more capable in low-light and having some decent blur on one end. Very proficient for general use, especially if you pair it with a prime that can offer even more blur and even sharper corners when you need it.