My wife and I had dinner at Myth last night to celebrate her birthday. In a word: terrific.
The decor is both beautiful and interesting (and very different from MC2) and there's a luxurious amount of space between tables.
The wine list is extraordinary and the sommelier is top notch. There are plenty of restaurants in the City with more extensive lists, but most of them seem to be more for "show". This list is practical - it's absolutely full of interesting wines at extremely fair prices.
The service was good but not great and if there is a weak spot that would be it. Our server was young and seemed a bit inexperienced, although in fairness she had a great attitude and did manage to get everything right. The kitchen was extremely flexible and was happy to modify a couple of dishes for us (my wife is a vegetarian and I don't eat pork).
I started with foie gras mousse on brioche which was delicious although not fully satisfying for a foie gras slut like me - I prefer a thick slab quickly sauteed. My main course was the seared lamb chops and they were absolutely wonderful - the best lamb I've had in a long time. My wife's salad was great and her risotto was very good. We shared a cheese course and dessert, both of which were solid but not showy. We also liked the portion size - more than "small plate" but not so much that we felt stuffed. The bill (before tip) was $88! I can't remember the last time I ate that well for so little money in San Francisco.