I've only played it in a few local Smash Bros. events where they had an Xbox setup to play Tekken 8 [first time was for a tournament and I even participated in it, second time was only for casuals] - Heat is cool looking although I've seen both faces of the coin

On one hand, I had got bamboozled hard when I had my first loss in the tournament against a skilled Nina as Heat allowed the combos to go even longer and eat more damage per mistake.

On the other hand, getting small combos and followups after using a DEATH FIST with Paul thanks to Heat activating automatically for some reason is HILARIOUS. I even remember that I accidentally got a back to back Death Fist combo in casuals because Heat let me do that. It's super goofy, but Paul is my main in Tekken alongside Heihachi [who I saw could do the same too when I tried it once], so it's funny that at least my brick-headed gameplay plan gets a sliver of benefit from the Heat system lol