i also read many negative comments on it too, but for $359 ( bought off qoo10 from a user called lodestar, took about 2 weeks to ship from USA), decided to just take the plunge.
If no phone, can just use ur key as per usual since it does not replace your deadbolt. It's just an add on to the back. it shouldn't give u much problems unless u have to 'adjust' ur door before locking it normally. (notice a lot of complaints form overseas user on this)
easily to install also, took me about 3 mins. after that is pairing with phone + update firmware about 10 mins.
at first i was concerned due to the app limit auto lock to be within 100m from your home (lowest setting) as its location based. i thought, what if i'm downstairs and it unlock?
but tried and tested it will only unlock when i'm about 1-2m away from my door. Am not sure about android though. i'm not a android user.
-edit- just checked, theres a faq on their website for android auto unlock. so I guess it supports :
http://support.august.com/customer/en/portal/articles/2166772-how-do-i-enable-disable-auto-unlock-android-
i've also added it to my homekit app on my iPhone (also paired with my AppleTV as a home hub) so I can remote unlock if my parents come over. there's also a setting to auto-lock it which i am using, so it locks itself after 2 mins (can set to fastest 30 sec if i rem correctly)
been using it for about 2 weeks now and really happy with it. there was one instance of it not connecting and auto unlocking when i left my phone in my gf's bag (usually in my back pocket) and had to take it out before it auto unlock.