Innate Sorcery is kind of like Rage for a caster. One minute of better spellcasting (higher DCs, advantage on attack rolls), two uses per long rest (or more uses if you spend 2 sorcery points after level 7).
With Innate Sorcery and Seeking Spell, you can get super advantage on attack rolls (total of 3d20 rolled). With the lowered cost of Seeking Spell, that makes focusing on attack roll spells more useful — although there are still not many attack roll spells (the problem with Sorcery Incarnate in playtest 5).
Sorcerous Burst is now a d8 instead of a d6. That seems like a worthwhile level of damage for a spell with flexible damage types, but where the burst damage is exciting, but not actually all that valuable in real terms.
Sorcerous Restoration is now level 5 instead of level 15, scaling up at giving 1/2/3/4 sorcery points at level 5/10/15/20, instead of 4 at level 15+ (playtest 5) or level 20 (PHB). While the amount is small at low levels, that's also when you're scrabbling for any sorcery points at all, so it still keeps you at least a little active.
Sorcery Incarnate is now a minor feature instead of a spell. It's tied to Innate Sorcery (free, or 2 sorcery points per use) instead of limited 5th level spell slots.
You still get to use two metamagics at once with it, but you don't get the sorcery point recovery (that's pushed over to Sorcerous Restoration) or advantage on spell attack rolls (which is now part of Innate Sorcery). Its main value is allowing you to use Innate Sorcery more than twice a day, which is a decent enough benefit.
Arcane Apotheosis gives you a free 1-2 sorcery points used per turn while using Innate Sorcery, which again is a decent amount of conserved value.
You have a total of ten metamagics, eight of which cost 1 sorcery point, and two of which cost 2.
You have 2 available metamagics at level 2, and gain 2 more at levels 10 and 17. Playtest 5 gave you 3 at the start, and another 3 at level 13, for the same total of 6. The PHB gave you 2 at the start, and 1 more at each of level 10 and 17, giving you just 4 total. Playtest 7 is a strict upgrade over the PHB, though a different distribution than playtest 5.
Also, changing out a metamagic can now only be done when you gain a level, rather than after a long rest (playtest 5). It's probably a power balance thing.
From level 7, you can use two metamagics at a time with Sorcery Incarnate. While it was hard to justify the idea of using two metamagics at once at the expense of a 5th level spell slot (playtest 5), being able to use two metamagics from level 7 onward just using Innate Sorcery is much more reasonable. I can see combos like a Quickened+Careful Fireball/Arcane Eruption, followed by a Fire Bolt, or a Heightened+Twinned Hold Person. Subtle+anything can always be useful, too.
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Overall, I think everything has been elevated up nicely from the PHB, and the really problematic bits of playtest 5 have been discarded. The loss of Sorcerous Vitality is a mild bit of sad, but I don't feel like it was truly necessary, either, so not that big a deal.
