Hi - I know you shouldn't use nested listviews, but had this working nicely - the only problem is that on android, if you tap an item in a nested listview, the ontapped event handler fires once... if you tap it again, the handler fires twice, if you tap it again, the handler fires three times and so on. This only seems to happen if you fire off a navigate.push to a new page in the ontapped event handler. This all works fine on iOS.
So, I thought I'd use a grouped listview. I don't really like how the grouped listview works as I need an ontapped event for the group header. I did notice that on iOS, if you tap the second group header, it selects the first item in that list and fires the ontapped event - this doesn't happen on android.
The only other problem I currently have is that performance on android is terrible - I'm writing a scoring application for archery, and the button clicks are shockingly slow to respond on a form with 14 buttons.
Apart from that, loving xamarin.forms (apart from the nightmares of learning new stuff) and looking forward to a more mature product.