The order the matches are played in is interesting. The favourites from this group (IMO) playing each other in the first match and the winner of that will almost certainly go through. South Africa can virtually assure a spot in the semis with wins in the first two matches which would make the scrap for the other spot interesting.
South Africa should definitely get through the group, despite their reputation for falling over in tournaments and the added pressure of being at home.
SL are good but with some obvious weaknesses in the lower middle order and the conditions may not suit them (what are SA limited over wickets like at this time of year?).
NZ have gone downhill a lot as an ODI side in the last year or so and to me the batting order looks all ass-about-face. The bowling is good (fitness permitting - our backups aren't so good) so if the batting works then we have a chance.
England have reverted to being rubbish in ODIs, or maybe that's a clever ploy so that SA, SL & NZ underestimate them.
I'm going to go against orthodoxy and pick South Africa and England to go through to the semis.