So what do you mean by worth? Looking at it competetively: absolutely not worth it. There are many way better decks for Mages (with or without Quest).
Looking at the fun aspect: you need to have mechs and you need to fullfill the quest, which can be done by spare parts from mechs. Building and trying a deck you will realise two things. First: Mech Mage works a fast pace. To even reach a point where you can finish the quest and get out time warp & mimiron you'll have to slow down and artifically keeping yourself from closing out the game (which gives your opponent opportunity to win). Second: you don't want the quest in your starting hand. It takes a card spot and 1 of your precious mana in the early game. You would much rather have another 1drop instead of it.
In the end this means: At the beginning of the game you are weakening yourself with the quest and at the end of the game you're doing it again by waiting for your combo to assemble. If this is what you call fun than yes, crafting mimiron is worth it.
I dusted Mimiron's Head and it was one of the few legends I never regretted doing so. Trsut me its not worth crafting that card. You will find yourself disappointed at how hard it is to pull of almost all the time. There are plenty of other fun legends that are WAY more consistent than that.