How to Rend Fiends and Immolate People: A Guide to Sorcery

[Flashy]

It does let you use your bonus action to disengage and move a total of 40' (assuming your normal move is 30') each round you cast a spell. It also let you move 10' before the spell, so you don't have the disadvantage of casting in melee.

Casting in melee isn't a problem unless you're for some reason casting a ranged attack roll spell, which would be a generally silly thing to do when you likely have a lot of other spell options. It's a handy thing to have when you want to disengage, but I really think EvilAnagram's rating is right on the mark.