After playing around with this card abit it's best described as Underworld Contact +1 & i am not just referring to its cost. At first glance it looks abit worse with the higher cost both cards require stuff to work 2 in one case 2 in the other.
However this is untrue as the difference is no runner has 2 to start with (at time of writing) so you need at least one other card for Underworld Contact to work but all runners starts with at least 4 spare so this card doesn't actually need any other cards to function. This alone makes Data Folding better than Underworld Contact especially if you factor in deck slots and cost for the other card also. You can even use this happily with a regular rig 3 programs and a console or Chaos Theory: Wünderkind. is actually easy to keep free with only minor +.
All in all it works fine if your rig leaves you with 2 MU free or you have the kind of deck that can have a huge rig but generally doesn't install it all or use that extra MU for more than a turn. (generally Anarch with Parasites and the like)
Drip econ that never run's out.
Works from Turn 1 with no Setup.
An easy fit if theirs nothing you want to use that extra MU on.
Can be a little slow.
Can be shut down or restrict what programs you can play.