Pros: little effort involved, baby gets on with it, food keeps them entertained giving you freedom to eat/drink at the same time, easy to feed in restaurants & cafes. I also found that by reading up on BLW and people's experiences, I felt much more confident in DS' ability not to choke, not to worry about precisely how much he ate etc.
Cons: some places are not easy to BLW in (eg carpeted places outside of home that aren't usually for eating in!), and a BLW baby may not be too keen if you try to spoon-feed in those circumstances.
The con I state probably doesn't come up for most people, but it's a regular factor for us so I have to try and pack the least messy handheld foods and very smooth spoon food (eg yoghurt). DS will try to eat practically anything self-fed, but if a spoon appears it must be smooth and he must be in the mood for it. If not, he'll pull the food out to examine it and then feed it to himself and his face and his hair and his clothes... 
We started BLW 2 weeks before 6mo, just with veg. FWIW we're not strictly BLW now, at 7mo we introduced porridge whilst exploring breakfast options - DS loves toast but wasn't keen on any of the other BLW breakfast ideas I tried. He loves porridge with fruit in the morning now, which is spoon-fed. Snacks are all self-fed, meals are largely self-fed although at the moment I do often offer a couple of spoons of something to see if he feels like it.