Initially when I saw the heat mechanics I was very turned off by the apparent direction of the Tekken franchise. I stopped playing T7 in late 2019 when Leroy was released and my long time sparring partner had quit the game entirely before that. Fahkumram was released later, following in the footsteps of Leroy's stupidity and braindeadness. What little tabs I kept on the game, everyone seemed to keep getting buffs. Better frame data, better range. New strings for even more wall carry for characters that didn't need them. If someone had a mid-mid string, they just had to get a safe-on-block natural mid-high extension. If a character didn't have a flip over wall combo ender for stupid damage they just had to get one for some reason. Even as a Heihachi main I could not agree with the buffs he received, more range on his jab? OK, but I dunno it seems a bit much. Df1 has more range? OK, this is just stupid, already one of the best 13 frame pokes in the game with extensions and now it's even better, why? Ws1 buffed to 13 frame start up? OK I guess, stupid change but seems in line with the rest of the stupidity of everyone getting a 13 frame while standing punish that knocks down and does hella damage.
After watching people play the beta and in this case, judging from Bryan as an example, it seems they have decided to tone things down a bit. Better damage and wall carry seems locked behind the heat system. Qcb2,4 and fF4 do not extend combos and fF4 no longer launches on counterhit, instead you have to use d3+4,2 and jet uppercut, the qcf4-series and b2-series still serve as a combo extender. Taunt follow-ups scale. F2,1,4 does 42 damage but post taunt it only does 29 damage. There are new srings but they do not lead to the same damage.
As for general system changes, backdashes seem to have been nerfed all across the board but sidewalking seems more effective for evading stuff. I was told several magic 4 CH's have been removed and get up 3 no longer launches on counterhit.
It seems heat will have 2 main uses, blow it all on damage and wall carry after you launch someone, or use it on moves to gain frame advantage and pushback. You could use the pushback on blocked heat moves and the dash that follows to escape your opponent's wall pressure or you could use it to push your opponent to the wall. Stages seem bigger than in T7. If all these changes succeed in limiting combo damage, wall carry and oppressive wall pressure I'd say the game is headed in a healthier direction. There are some oddities like Kazuya's new df3+4 series and the last hit doing absurd damage but that will most likely get nerfed. Chip damage on big damage moves on block and recoverable health are there to encourage aggression but I don't think they are going to be as impactful as people are making them out to be. The pace and flow of the game seem the same as in T7.
I don't think anybody wants to go back to or keep playing a version of Tekken that's like T5
R or Tag 2 where you are handicapped unless you can skate around the screen with Mishimas, abuse sidestep-block and chuck electrics with impunity and it doesn't matter if they hit, get blocked or even whiff since you can barely whiff punish an electric due to the fast recovery unless you also have an electric or a fast long range shoulder like Paul, Feng or AK. Especially now when hitboxes are allowed in tournaments that type of playstyle would just be too good. Try playing against a good hitbox player using Kazumi in T7 on an infinite stage and you get a sense of how lame that is.
All in all if you liked previous Tekken games you should like T8 once you get used to the game systems. Now we will just have to wait and see for our first T8 original character designed for the new system. I really want them to stay out of braindead design choices like a million strings with different enders or cancels that lead to command dashes with mix-ups and plus a million on block 50/50 guessing situations from heat dash, armored launchers and other MK X style crap.