Sigma 24-135/2.8-4.5 opinion?

I am considering getting this lense, Sigma 24-135/2.8-4.5, for my Drebel. Anyone with experience with this lens or know of reviews or anything good or bad about it?

This would give me a zoom with 38-200 effective focal length with lower than normal appeture values.

While I'm at it, this lens isn't much different but a lot cheaper: Sigma 28-105/2.8-4.0

Thanks.

I have it and use it for a general walk around lens. I have had problems with soft focus, or out of focus shots. Still, for general photography, it's my favorite lens. I just find that I have to be very careful with my settings.