Are those straightening brushes worth it?

[GlitterUnicornsAndAllThatJazz]

Two questions:

1. what makes them better than straighteners?
2. which one(s) have you tried and liked?

I have something like this. It was a Christina Aguilera one from Lidl for £16.99, but this is similar. I leave the house now looking like I’ve had a salon blow dry. It’s great.

www.johnlewis.com/babyliss-2764u-flawless-volume-hair-styler-black/p3607437