I love the New Sona and I am unashamed.
I love the new Sona. Absolutely adore it. Sona was my second main a long time ago. First one I played in a proper roll. Before that I picked Rammus and went wherever. Anyway, Sona is amazing. But she was just float around with an aura on for most of the game, and that got boring. With the new update, I'm getting back into her, because she still functions on the same principle (auras and working power chord in your favor), but now it's actually constantly engaging to play her. When you use what power matters, rather than just spamming qw in teamfights. The new kit is amazing, basically. It fits Sona but it's vastly more interesting.
Yet people have tons of issues. Partly because it takes a while to adapt, partly because Sona is over-tuned. She has devastating poke if you pull it off, but zero survivability if she gets caught out while poking. This is a bit painful early game, but it can be built away, but people don't want to build it away because they want more AP for better poke/shield/heal/speed. So I think her stats just need slight adjusting.
Also, tangential piece of advice. Build Iceborn Gauntlet on Sona. AP, mana, armor, and CD are all stats Sona benefits greatly from, and the passive gets absurd. If you proc the passive with a Hymn of Valor powerchord, it's her basic attack damage+the bonus on-hit damage from Q's aura+150% of power chord+125% Base AD+Slow aura. It chunks like crazy, especially if you get more AP from some other items.