It's alright. Not op, but ok. You can actually use more than 3 spells per laning phase, but it's not spammy either.
Lost Chapter / the following items get you into a pretty ok spot. And if you're a hard spammer you buy Archangels, which gives 1400 Mana and makes you 25% more mana efficient.
If I really want to spam I'd probably take it when offered, but having a useful jungler that isn't underleveled is usually the better choice. I guess if you are planning to shove hard, it's pretty neat. Like for example an Anivia that is after your turret plating or something.
Oh yes. And Manaflow band became practically non-competitive, due to the removal of Ultimate Hat from that Rune Tier. So you're usually decked out with Doran's Lost chapter, and a carefully stacked Manaflow Band