I find not too bad, but I can't say conclusively it's sharp.
Have a look against my 18-50 F2.8, which I consider a sharp lens, almost at the 50mm end. So that you can compare and judge for yourself to see if your lens is sharp. Yes I know, it's a badly taken photo. but.. ah well..
I can't find any central focus photos, but here's a side crop. Absolutely no editing done to either image.. Original posted just to show you how side the crop was. You can make your own conclusions ya.
Side is supposed to be softer then center right? Note though, different lighting, different handheld speeds may affect sharpness..
Then I think it's ok. If you stick with 6mp, it is ok, the lens seems to be able to resolve beyond that, but how far? we can't tell unless you use a higher pixel count. But judging from the image, I think 8 to 10mp should still be acceptable.