Who is opportunity and callers on Whats' app could not live without, is in good hands here. If you have at home wireless, to get even loose with 200-300 MB per month clearly and Apps invites not go down.
The optional foreign option makes me happy. The last holiday in Majorca, I could surf daily budget for 2 / day with 25 MB, without falling into a collective-trap. The best: the charges were incurred only on the day of use! This SIM card I use with my iPhone and whosoever still enters into an expensive contract with the giant pink or another D-network operators is your own fault.
Certainly the O2 network has some weaknesses - which I suppose but because of low maintenance costs gladly accept and financiers me with the savings the next smartphone!