How better is the DA 15 compared to the kit lens?

Currently, I am a bit limited with my lenses for landscape photo. The kit lens isn't very wide, and surely not the best at 18mm (even if I'm quite happy with the result).

I also use the 10-17 fisheye, but I have most of the time blurry borders. It's alright for fisheye fun, and 180 angle of view, but not very usable for normal landscape photo (have I a bad example?)

So, I'm looking for a normal wide angle lens, but I want a small and light lens, which can go in my current travel bag. Therefore, only the DA 15 seems to correspond my needs (I also excluded the better normal zooms, because I like the lightness of the kit lens a lot)

But seeing the price of this prime not so wide (compared to wide zooms), I prefer to be sure before buying that it will really be a big improvement from the kit lens, like the difference I have on the other scale of the kit lens with mine A 50 1.4

--
PBY
http://www.flickr.com/photos/pby/