It is not a great lens or an L lens. It definitely has its flaws as described above. And it is in my dry box most of the time. Perhaps its main weakness is sharpness at infinity.
Recently I took it out for a lens test (MLU, cable release, tripod, etc) against my 16-35 and I was really shocked that it produces incredibly sharp images at short distances. While the 16-35 won the contest, I began to question my sanity since the 16-35 cost more than 20x the 18-55. The 18-55 of course thrashed all my third party lenses at that short test distance.
There are not many lenses that can give you 18mm focal length and that level of sharpness at closer distances (1m-5m, can't comment beyond that). I had several of my pictures blown to poster size and quess what, the picture taken by my 18-55 beat the one by my 100mm macro, (both handheld). While this is not a fair comparison as the 100mm is liable to handshake etc, both were taken under similar real outdoor conditions.
So the 18-55 has earned a permanent place for itself in my drybox, since there is little loss in keeping it and selling it would only yield me a few dollars. Hope those of you who still have this kit lens will cherish it. It is not a good paper weight as it is rather light, like my 50 f1.8.
Perhaps I was lucky to get a good copy as I have heard that the quality vary widely for this lens.