Yes, i was not pleased when i found out the Lily's were attached to bum spells... aaand i still think the system would work better if other spells like Regen at least offered a chance at Lily's, but the whole thing is smoother than i expected, and in concept, i actually enjoy the job more than i did in HW.
The reduction on cool downs just feels outright powerful. When i'm mindful to keep my Lily stack at 3, the frequency at which Assize pops for example seems to come very quick... and regen, frankly, i can pump out powerful spells and not run low on MP near as fast as i did before. ... popping thin air and shortening cast time and regen and spamming Medica xD it's like i can be at 0 MP, wham bam super AOE heal blast fun time and suddenly have 10k mp again.
Now, again, i do think it would be better if Lily's came from more variety of spells. Too often i'm focusing a little too much on throwing out a cure spell to get a Lily when i would have maybe wanted to use those few seconds for something else ... but there's also often enough cause for the use of a Cure spell to produce Lily's naturally. It depends.
Mainly, there's no real issue with how long they stay up. ... Except that they do vanish as soon as i use a cool down. And what i mean by that is i do wonder if the juggling act is a bit too complicated for its own good knowing i have to get Lily's back up every time i pop anything. Again, if Regen for example even offered like a 25% of a Lily, i think the system would work better.
But in all, i'm pleased with it. The WHM cool downs are strong, and shortening the recast timers sometimes feels like it can border on super healer power breakage when the Lily's are maximised perfectly ... even if the DPS is a bit lower.