Not really a fan of this offering as much as I was the Artificer. For one, I find it weird as others have mentioned how they seem to be nudging the sorcerer towards a pseudo melee role, which it still can't fill effectively with their minor HP bumps and such. Also strange is how none of these really interface with metamagic in any way.
Favored Soul is alright, I actually like that they lost the winged nonsense. Cherrypicking from the cleric list is dangerous though, I hope that gets curtailed somewhat. The save/hit bonus is generic as hell but still useful, while the skill bump at 6 doesn't do much other than make the party face even face-ier. I do, however, think some have undervalued the poison immunity, as that's a super common damage type and condition.
Phoenix straight up needs to be able to rock the mantle more often. If it has to lose the damage buff initially and regain it later so be it, but I think this is one of those things that shows the cracks in the subclass system, much like the Arcane Archer, in that it's too restrictive with what should be the iconic ability of the character. Phoenix Spark is pretty good, free damage and you stay on your feet, which is always preferable to the alternative. Possible risk of friendly fire, though. Nourishing Fire is potentially a problem, given how many HPs that could restore on a chassis already designed for blasting. That said, its effect is wasted if the sorc is at full health, so we'll see.
Sea is the best of the bunch imo, if I'm reading the curse right it seems designed to facilitate switching between cantrips and full spells, which is a neat playstyle that's not unduly complicated. Most of the other perks are thematically appropriate and mechanically useful, so not much else to say here.\
Stone sorc is amazingly bad. Firstly, and most importantly, because its existence lessens the chance of a full swordmage class being released. Second, because I highly doubt it can do what wizards seems to want it to do.
First off, it forces you to heavily prioritize Con if you want a usable AC, which also falls off if you get incapacitated, and takes an action to restore. Second, despite essentially being given a d8 HD (which it actually doesn't for recovery purposes), it receives even fewer fail-safes against damage than Sea sorcs do. Third, the Aegis requires an ally to be hit by a melee attack, and then you also have to make a melee attack as a sorcerer and hit to benefit from it...which actually means you need a decent score in strength or dex to make decent melee attacks, or find some way of adding your charisma to it with spells like Shillelagh. Fourth, Stone's Edge is just an incredibly generic damage amp, only loosely thematically appropriate with stone and has a complete lack of synergy with the swordmage element of the subclass. Even the last perk at level 18 is generic, if likely effective.
Stone really irks me. It doesn't live up to the swordmage from 4e by any means, and I have very significant doubts that it ever can when shackled to the sorcerer chassis, a class that really doesn't want to be locked up in the thick of it. Phoenix and Favored soul could use some minor tweaks, and I'm pretty pleased with Sea.