Is it worth doing the trials?

Yes, definitely, you will get the gold DNA coins from completing trials which you can use for certain evolutions.

You also get some EXP and other rewards, all in all, these are really essential to do in order to progress in the game.

I like to do the trials after I complete a chapter, before attempting the next main chapter.

Good way to grind for resources and progress at the same time. Much harder, provided.