There are 2 things that may catch-out pilots on first moving to Fenestron tails. Nothing to be frightened of, just understand the physics of the machine you are flying and act appropriately.
One is that the thrust increase / peddle position is not linier, as shown in the Eurocopter service letter (link above), and the amount of pedal input needed is therefore much more than the un-initiated might expect.
The second is that the Fenestron tail is aerodynamically shaped - it is a wing - which provide anti-torque in forward flight. The total anti-torque provided to the pilot is therefore the sum of the tail and the fan. On approach, as speed bleeds, the thrust provided by the tail will reduce and without action by the pilot to replace this with additional fan input the heli will begin to crab through inadequate anti-torque (to the left for EC120, G2). If you let this start then peddle input to correct the crab occurs as speed continues to bleed on approach, further reducing the effect of the tail, and it is easy for the novice Fenestron driver to underestimate the amount of peddle needed to deal with BOTH of these events. As a result the crab worsens despite (inadequate) peddle input. Then something horrible and very sudden can happen: because the Fenestron is a "wing", the crab is changing the angle of attack. When this reaches 20 degrees the "wing" stalls and in an instant the driver loses all of the anti-torque provided by the wing, being left only with the effect from the fan. The machine was crabbing anyway (insufficient peddle input) and suddenly it will snap into a (fairly violent) torque spin.
Torque-spin like this can be controlled - bury your power foot (right for EC120, G2) to the peddle stop and keep it there. It will likely take a couple of revolutions to control the spin; but it will IF YOU KEEP YOUR FOOT TO THE STOP.
All helicopters have operating parameters, so fly within them. Do not let Fenestron machines yaw to torque as you bleed speed on approach, use the appropriate amount of power peddle early.
In several years operating EC120s I have not ever had a machine snap into torque spin on approach, though I did abandon 1 approach in my early days on type because in the particular conditions I was not quick enough to control the yaw on approach; rather than take a chance by continuing with a boot-full of right foot I simply added speed and went around. Not my finest moment - and didn't make that mistake on the subsequent approach.
Take a G2 flight with an instructor and he can demonstrate all this to you.