My thoughts:
-Putting a gacha system in an SRPG is a very neat idea, and the summoning is implemented well.
-Switching between characters in the overworld is awkward. Also, trading being unavailable seems kinda pointless, it just leads to more character switching.
-The summonable characters are interesting. I liked the mythical characters like Arthur and Merlin. I honestly wanted to learn more about the generic summons.
-Having your summoning pool be the enemies you fight makes your units feel less special.
-The leveling system is odd, or maybe I just don't get it. I understand that grinding is kind of a necessity in a gacha game, but units seemed to mostly level skill and not much else.
-I was not anticipating the final boss being so hard. It seems nigh-unwinnable unless you grind specifically to beat it, while keeping all your strong units alive.
-The humor's great. I loved the goblinfan dialogue. I also liked that you could summon goblins. I've been saying for years that I wish there was a game that would let me go goblin mode.