The new AST is a perfectly functional job that can do content. You can participate in the normal healer gameplay on it and be quite effective, with the only achilles heel being that MP management gets pretty tight.

It is also a complete mess of a design with little fantasy, a card minigame "mechanic" that barely engages the user or interacts with the kit it is a part of, and has precious few cooldowns that feel satisfying to use.

They'll go back to the drawing board eventually. In the meantime, it is something slightly different to do from Scholar or White Mage.