After a lot of youtube demo watching and debate I finally gave in and bought the Babyliss Pro Curl Secret (it was on special at Clicks for R1199, not sure I would pay the full R1599 for it though.. thats a bit steep).
But I can say for me it was so worth it!
my hair is quite long.. mid back and it curled it amazingly!..no tangling or getting stuck like some reviews have said. and it was so quick and easy!.. my entire head was curled in 10-15 mins (and I have thick hair).
It even alternates the direction of the curls so they dont all lie in the same direction.
It also has 3 temperature settings and 3 time settings allowing you to control the tightness of your curls.
The curls were so long lasting too.. with just a bit of medium hold hairspray I still had curls the next day when I woke up! (my hair is naturally wavy though so it isn't dead straight to begin with).
The only con I have found to this product so far is the high price.
I must also note though that it barely worked on my sisters hair at all.. even on the highest temp it made a slight curl which fell out within minutes.. so it would be a huge waste of money for her.
I also tried it on my mom's hair which is short (just touching shoulders) and it worked but it really didn't look good, so its better for girls with slightly longer hair.

This curler is fantastic but it isnt for all hair..
girls with very long (past mid back length) hair,
girls with short hair (above shoulders),
and girls with uncoloured hair (coloured hair has a lot more grip to it)
...you may want to somehow test it first before going to buy it.
and if you cant try it and your still not sure, my view is that if your curls dont hold with tongs they probably wont with this either.