LS XF50 Performance: How does it compare to other V6-powered sedans?

I'm curious to know how the LS XF50's V6 engine stacks up against its competitors. How does it compare in terms of power, fuel efficiency and refinement to other V6-powered sedans like the IS F's 5.0L V8? Does it offer a unique driving experience or is it just another mid-sized sedan with a V6 under the hood?