Alright then. I've recently entered Tremode after a long 10 hour session and have some complaints & suggestions based on my experiences.
Tremode needs a notification after defeating Moonlord
Simply having a message to show that Tremode has begun would honestly make entry feel more impactful.
Tremode needs to br more noticeably impactful.
After entering Tremode I've thus far noticed very little changes which lead me at fist, to believe the Mode didn't activate correctly. Another point is the enemies have remained practically the same and any encounters with Tremode enemies has quickly ended due to my ranged gear.
A possibly unfair comparison is the change from Normal to Hardmode which is more how I invisioned Tremode to work, with distinctive progression and the feeling to prior gear having little affect on enemies.
Possible gameplay & Content
I'm still new to Tremode although the content has seemed lacklustre. The lack of content could result in issues with progression moving faster than intended and the gaps between your damage and health closing quickly to the end game enemies.
I think Tremode is fantastic and if done correctly could make Tremor even more fantastic than it is. I'd love to see enemies absurdly high numbers when running through Tremode to counter the DPS that reigion of the game allows.