I was given to believe that my life as a sometimes Fuji camera system user would not begin until I jettisoned the "decent" but underwhelming 18-55mm "kit" lens and bought the real Fuji prime lenses. Then I'd be able to realize the potential of their "awesome" sensor...
But I'm a bit of a contrarian so I've been using the "kit" lens nearly non-stop. Yes, at a wide open aperture it does vignette a bit. But what do I care? I didn't buy the lens to shoot flat art documentation, or brick walls. I've also heard that it's very, very sharp in the center but less "convincing" in the corners. And they say that as if it's negative thing. I'm thrilled that it's sharp in the center and I'm happy I don't have to worry about distractions in the corners.
Oh hell. Just try a lens you are interested in and see if it works for what you do. Most reviewers; like the dim bulbs masquerading as technical experts at the big website, have a weird set of parameters for "measuring" the value of lenses, but the stuff they think is important; like dead even exposure across the frame or total lack of field curvature, are part and parcel of some of the best lenses ever made.
Bottom line. I think you can do great work with this kit lens. You might save yourself from some carpel tunnel syndrome and you might save some cash by passing by the "prestige" lenses and learning how to best use all around "good" lenses to make photographs.
These two shots are handheld, in low light, and shot with the aperture of the 18-55mm lens wide open. It's pretty much a worst case basket of settings for any lens. But with a centered subject all I see is sharpness and clarity.
I finally believe it's true; you can "over buy."