.....Yeeeaaaaahhhh. Nerf Sona Mid.
To be perfectly honest with you. The mid sona thing was always gimmicky, it sill is gimmicky, but now it's honestly very oppressing. I don't think her mana costs really match up that well with how much damage she is able to put out per cast. Other champions who likely do similar damage end up having mana costs of around 60 at least, going upwards to 70-80.
The fact that sona just has this "area" around her that punishes you for getting to close, (much like the soraka of past that people complained about, with starcall just having the 'bask in my presence and die' vibe to it) is pretty damn frustrating to deal with, especially for close ranged combatants who have no real counter to it other than jumping on her to force her away. There is no real way to "outplay" her Q, you can't dodge it. You can't divert it. (unless something something yasuo). So if you are in range, it's gonna hit ya. If you were in range of that you were also in range of her auto attack too, which does actually more, than the spell it self. (which is fine, forces the follow up and shiz). However, the primary point is there is really nothing you can do about it cept get hit, and hope she OOMs eventually (with a 40 mana cost, that takes a while).
Her heal isn't that impressive, early game or otherwise, bit it "is" enough to prevent a bursty character from destroying you in lane. The real thing about her is that her shield from the heal she does gives her "even more" temporary HP. I forget actual numbers but you can mitigate "a lot" of dedicated damage to you with this alone, not to mention she can cast it multiple times in the same fight, making it outstanding sustain.
That's.. really all I have problems with. Seems fine. But nerf the numbers. Fucking PLEASE.