No catch. Unless you download more than 1TB then speed will be capped at 5Mbps until bill cycle refreshes.

Not a gamer, cannot answer.

No issue with streaming. I stream YouTube on laptop and movies and other stuff using my Android box.

Oh ya, it doesn't support P2P.

I've been using it for almost a month now - Nexus 6P as a mobile hotspot.
Here is my overall feedback.

I'm a regular Overwatch player. The ping is at around 40-60 with no spike and delay when i'm playing it at Old Klang Road. No issue with Dota as well as it runs with decent ping like OW. (although i have stopped playing it)
No issues streaming on Youtube and Twitch either.

However, the network got worse when i'm at Bandar Utama - network is congested in that area. So, i need to find a good fengshui in my house to position my phone in order to get good speed/ping.

Your mileage may vary depending on your area and my experience is solely based on mobile tethering.