Pros
Summation effect - protein synthesis levels are elevated after resistance exercise, and can be elevated further (summation) if you workout again whilst they remain elevated.
Nutrient partioning - more of your cals will go towards building muscle and glycogen replenishment rather than fat storage. The significance of this is debated (i.e. the magnitude of partioning).
Same volume spread out over more workout = less fatigue as the result of individual workouts.
Cons
Strength loss - you may not be able to maintain your xxRM strength levels, probably an increment or two lower. This is probably dependent on the volume per session - keep it to one set and I doubt you'll notice this. Two sets almost certainly when you hit the 5s.
Depending on your body, age etc, some people report this is murder on the joints. I actually felt fine.