Played a few games, Sona still has some big issues.

Let's start with the good. The mana regen buff and the new mastery pages do a lot to help . The bonus heal and shield is nice, and the bonus resistances can really help. The bonus up time on her Q is much loved, i no longer have to worry about pin pointing the EXACT moment my allies get the buff, so they don't either waste it or it falls off before use.

Now the bad:
She is still WAY to slow in the early to mid game. Until you start stacking a bunch of CDR you still have zero chance of out running anyone.

Her heal and shield, while better, are still very unimpressive. I still find myself barely making a dent in my allies health pool when i heal them. With a 10 second cooldown i would hope that each heal would have more of an impact on the game. Also the shield still has in HORRIBLE up time. You made the damage boost last longer, how about some equal love to the shield. Make it last like 2.5-3 seconds.

She is still gated by needing like 30% or more CDR to function. Your spells are all based around doing something often, rather then doing some really really well. Once you get past the early game, your damage falls off, your healing is almost never up when you want it, and your horrible base movement is made even more painful by the super long periods of time between speed boosts. All these issues persist until the late game / you get 2-3 CDR items. I know some champions are gated by items, but it's usually 1 item not 2+ high end things.

Finally her aura range is still garbage. 350 is just to tight an area to function as a reliable teammate buffer. The tight range and low base movement speed often means that unless you are already bunched up with your allies, you will be unable to tag many of them simply because they are faster then you.

On a side note, i still really wish her Q bonus could be used on structures. The lack of aggressive lane pushing power is still a big power gap from her pre-rework days.