Setup was amazing in how crisp it is including automagically integrating via HomeKit. I am just starting out with an Eve Weather and after setting it up which took nearly 1 minute (the "difficult" part was realizing the batteries needed to be installed). As soon as it was enabled and I approved HomeKit which also required I use iCloud Keychain (I thought I had already enabled it months ago when I actives my new 6s+ at the time).
Adding others to have access to Eve Weather was just as simple but honestly the logical thing is it Apple automatically enabled family members that I have via iCloud Family Sharing. Still it was simple enough. You can add/invite via the Eve app or via HomeKit in Settings.
The whole thing is so wonderfully simple I feel like I must be missing something. Now Im lusting for either an Eve Room or perhaps even dumping my Nest Thermostat (v2) which seems like a dinosaur not having HomeKit and lacking features that EcoBee3 or other new HomeKit enabled thermostats have. I hoped I would be able enable triggers and conditions with Eve/HomeKit and its all super easy and accessible via the Eve app as its fully integrated with HomeKit.
Dookie 2x about Eve for Matter & HomeKit, v2.0