I thought about buying this lens before. IMO having that range in one lens would be very nice for some situations like travel photography. The weight doesn't bother me in the least, and considering the 28-300mm range the price seems reasonable. A Canon L lens kit that covers that approximate range will exceed what the 28-300mm sells for and add to more total weight to pack around. Even though there were some appealing aspects in the end I decided that the IQ was the deal breaker for me.
I can see how for some people the lens would be a perfect fit, at least for certain jobs.