I've been really excitedly awaiting Rage of Elements- more element-thematic spells, along with loredumps on the elemental planes and an entire new class, the Kineticist, which I've been very eager to get my hands on. I've only looked into the class partly, but I love everything I've seen so far! They're an interesting take on a Caster, with the ability to do a little bit of everything if they want, but an obvious push to try and specialize into making your kineticist fill a particular role. You're always capable of blasting, which is great! The ability to aid allies, control the battlefield, deal AoE damage, and even heal is a blast (aha.)
I don't play many casters, but the Elementalist Class Archetype seems really interesting! I like the variation of eastern and western classical elements being the options you can choose from, and the feats seem like they'd make an elementalist very enjoyable. Letting a Druid replace their initial Order Spell for one they might find more thematically appropriate or useful is a definite win!
The variety of Elemental-oriented backgrounds are interesting. While not as exciting as lore, or class and archetype options, it's still great to have and enables characters from both a mechanical and a flavor/story standpoint! Of course, Heritages are a wonderful addition too, so I'm excited to see both.
Unfortunately, I don't feel like I can say in good conscience that the book is flawless. There's some bizarre choice in wording that leaves certain effects unclear (Is Flinging Updraft used on an unwilling target Forced Movement? I assume so, but the specification of Jumping is bizarre. Is Tremor's 1d8 damage a typo, or is the +1d10 on heighten a typo?), or just outright impossible to use without a table adjustment (Roiling Mudslide's area?)
All in all, lovely book. Great content, interesting class with a pretty unique playstyle I'm excited to use, but the typos make me glad I didn't buy a physical copy. It'd kinda suck to drop almost 60$ on a book with what looks like a decent number of typos and errata that'd need to come on the heels. It'd be 5 stars without typos, and 3 stars if the content wasn't so nice I could ignore the typos. I probably wouldn't be as happy if I'd paid almost 60$ for a physical copy, though. Also really wouldn't mind getting an updated PDF- both for typos and errata, and maybe slightly higher definition images.