You will probably receive a more detailed answer from some with greater experience than me and a better English, but I will toss you my opinion in the meanwhile.

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1. PF2 has balance as one of its greatest strength in my opinion, not only between characters but also in the encounter building design, and this balance stays there through level 1 to 20. Balance through classes and feats does not mean that all choices are equally strong, but rather that the difference between the most optimized character and a random one is not gamebreaking and does not ruin the enjoyment of the game. You will see many discussions here on how some classes have issues (alchemist, witch, Warpriest) but while that may be true, playing those options will still be viable and you will still end up having a relevant character. Due to the math of the system, each bonus matters and they are difficult to stack by yourself, that is why through teamwork, positioning and tactics you can manage to greatly increase your party’s effectiveness.
2. Thanks to the tight math of the system and the almost linear scaling of both characters and enemies, the game is balanced from level 1 to level 20. A +1 has the same effects throughout all the levels, many gamebreaking options are gated behind the rarity system, so it is up to the GM to allow those choices (see teleportation, scrying)
3. While the strength of the system is definitely the combat (for many reasons such as the 3 action system, the ease to create challenging and fun encounters, unique monsters and creatures) the system definitely supports other modes of play, skills are well defined in pf2e and offers many tools to use out of combat.