It works alright. Sometimes it works really well, but I just tested it out now for a short trip and it suggests going too many stops out of my way to get a citibike. Not sure why, as there are bikes available at closer stations.
I also don't think it supports the idea of "I have a bike". It's mostly transferring from public transport to a bike share and vice versa.
> Bonus points if they build in cost optimization, ie, "take the train 80% of the way there and then Uber for the last leg,
It does do this (or at least is doing it in my current test). If I ask for directions from home to LGA, one of the Labs options is to take the G to the 7 to Junction Blvd and then take an Uber for $10-14. An UberX from my home to LGA right now costs $24.60
Getting all that data for a single city would be impressive, let alone around the world.
Not that Google couldn't do it of course.
Bonus points if they build in cost optimization, ie, "take the train 80% of the way there and then Uber for the last leg, optionally saving you 20 mins for an extra $8, or bring a bike to save 10 mins for no extra cost". I'm reading that Citymapper might do this in London, but I've not seen it in their NYC version unless I'm just being dense?