A few years ago, BSM used these for a year as well as some Punto dualogics. Generally they behaved well, but when learners were practising manoeuvres the clutch would overheat, then you're stuck for a while until it cools.
In normal use, this should not be a problem, but if your normal parking manoeuvres, at home, work, etc, involve shunting a few times, then this may not be the system for you.
Whilst you are learning now, practice the manoeuvres so that you can do them well, with a nice smooth flow, so that time is minimised without compromising safety. This will help generally, and especially with any automated manual system.
As suggested above, a good long test drive is needed, to your home to practice reversing onto your drive, if applicable, or anywhere else representative of your normal use.
The Fiesta uses a 'conventional' autobox with a fluid drive, hence the term 'slushbox' sometimes used. These work nicely, but use a little more fuel. The Corsa also can be had with such a system, but can also be automated manual, so ensure you have the right one.
Good luck, with your choice, and your test. Your instructor may have experiences to share, so ask him/her too.