How do you say this is so much fun in french?

There are a few ways to say "this is so much fun" in French, depending on the context and level of formality:

Formal:

* C'est tellement amusant! (This is so much fun!)

* C'est très agréable! (This is very enjoyable!)

Informal:

* C'est trop bien! (This is awesome!)

* C'est génial! (This is great!)

* C'est vraiment cool! (This is really cool!)

* J'adore! (I love it!)

* C'est super! (This is super!)

You can also add emphasis by using the word "vraiment" (really) before the adjective:

* C'est vraiment amusant! (This is really fun!)

* C'est vraiment génial! (This is really great!)

The best way to choose the right phrase depends on your audience and the situation.