I was initially going to hop on this at midnight, but the scores being all over the place has me feeling hesitant. I may wait for some more gameplay videos or something.
I think how much you get out of it really depends on how much you enjoy these sorts of games, looking at what Tomomachi has offered me in the past 24 hours, it's certainly not got the insane level of item collecting that Animal Crossing has and is a bit limited, but if your looking for something slice of life, that isn't demanding you put the hours in for things like fish and bugs, and can easilly fit into a 5-10 minute play window. Tomodachi is worth the punt.
It's certainly not a game in any traditional sense. There's no goal or much in the way of playing, you just set a bunch of virtual characters up on a island, set their personalities and see where it goes. Player interaction is generally on encouraging/discouraging a characters stated intention, or fufilling a need.
It's something I can see myself jumping into regularly, and assuming that theres no penalties for skipping a few days. That might make it last longer than Animal Crossing, where the need to keep checking in usually turns me off once I start to get bored.
Side note: there's a Spotpass Marathon outfit now available till the 15th of June for EU. The spotpass notification will open your import store + allow you to buy your own island import item