I've been to Creamfields here a few times over the last years. It's good. Very different from a UK festival, very different from Creamfields Liverpool.
I really enjoy it. The key pointers are to go with a group of friends (5-15), organise a minibus to collect you after (you will be stranded if not), and expect to get lost- one of the charming things about this festival is you will somehow always find your friends again.
Buenos Aires is well known through though tour circuit for having passionate crowds and Creamfields exhibits this well. It is relatively small, 50-60k, with relaxed VIP areas with good group prices. It is one night only from 4pm - 4am. I usually get there for 10pm. It's enough as the ball keeps rolling until 6am usually en situ, and after there are many after parties back in the bubble neighbourhoods.
There is a great mix of artists and little queue to be had for toilet or Drink. Food queues can be long though.
As with any festival like this, the drugs are pretty important. Plan them well. Security is a quick frisk for bottles and other more voluminous contraband.
Keep both parts of your ticket well guarded as you will need them both to pass through different layers of security.
A superhero costume usually goes down well. B)