I went for the FQC line recently as Sona/Cait versus Janna/Ez. Gotta say, whether due to skill differential or matchup or the item actually being good, we stomped pretty hard. They were duo, not insignificantly higher ranked than us, too. So it's not a cripplingly bad item, at the very least, and certainly seemed to help make poke stick even harder against sustainless lanes.
The FQC line is currently a really good line for the supports who like to keep harrassing in lane, and finally build it up to an item with such a good passive and stats for the support that scales decently with AP. The extra 10 damage dealt by the spellthief's is huge early on during the laning phase. You will be such a big bully with that item, and it only gets better.