Walked around for about 3 hours today. Ran into a whole lot of people playing the game as well. Fun was had.
Until I tried taking over gyms that was. This aspect of the game is incredibly broken at the moment. I don't know if it's just the battle game mechanic, server issues, or a combination of the two, but I wasted like 20 revives and health potions on battles that ended with the enemy Pokemon becoming invincible at 1hp, and mine continuing to take damage until all of my Pokemon died or I closed the app manually.
Has anybody had any luck with gym battles? I won two consecutive battles at a nearby gym, was 1 battle away from defeating the team who occupied it, and then I encountered the bug I described above where the enemy Pokemon became invincible with a sliver of health left. I closed the app, came back, and despite the battle breaking, the game still made me heal and revive my Pokemon. I tried to battle again, and the big "GO" would show up on the screen and then immediately back me out.
What's the purpose of beta testing this stuff? Now everybody who occupied these gyms at the start have an advantage due to how broken the battle system is.