Ive had my first game with my Seraphon on Saturday in the Path to Glory campaign, it went to a draw because he couldn't catch my units and I couldn't destroy his. The objective was to eradicate the others Army.
Someone there (not the person I was playing against, he was super chill) called my Skinks broken because of wary fighter and doing what they do best, waste turns. Also Summoning and Teleporting was super broken aswell according to that person, never mind that everything got eradicated in melee and couldn't put up a decent fight.
Sadly I had not painted up my Bastilladon or Carnosaurus, or I maybe have had a chance on killing something, made a lot of mistakes aswell, but hey first real game, and my third AoS game in total.
So theres always something thats broken in the eyes of someone.
Personally I'm looking forward to that Tome, from what has been shown it looks decent and lots of stuff to play around with. I like that I can field either physical or ethereal lizards and that they each offer a different playstyle. In my books that prevents the Army from going stale too fast.
But that still remains to be seen and I certainly do hope that they retain the starlizard teleporting summoning playstyle, just a bit more optimized that they can hold their own on the battlefield.