I've had the Ring doorbell 2 for a few months now and pretty impressed with it Although noticing that quite a few delivery drivers haven't used it in the last few weeks.
If your going to get one, be aware that you will need to connect it to your WiFi network which was a problem for me as the WiFi signal from the main router (around 2 meters away) wasn't good enough for the Ring Doorbell and would result it it not connecting quite often. As i had a spare Netgear homeplug and SonicPoint access point i set these up in the hallway directly above our front door and the Ring doorbell now has a perfect connection to the WiFi.
I'd also recommend connecting it to your mains if possible instead of running off batteries as depending on what motion settings you use they can really eat the batteries up. I'm changing mine at least once a week at the moment which is easy enough and the Ring app on mobile devices does warn you when the battery needs charging / replacing.
Overall, i'm impressed with the quality of the Ring doorbell and ease to use it. Really handy to see / talk with visitors before i even get to the door or when not at home. Pretty good security device i think as records everything at the front of my house and saves it in the cloud as i pay £2.50 a month for them to save videos.
My brother has been looking for this type of camera but didn't want to pay the high price. He also wanted something that he could hook up to his NVR CCTV. He's just orderd a yoousee door bell for 57 quid including a USB dongle. Although I'm not interested in getting one myself i'd still be interested to see if its any good and thought I'd mention incase anyone is in the same boat as my bruv.
They serve their purpose and I guess a lot of people like that they can see the cam on their phone and get push notifications. They are proprietary, so you have to use the ring service which means paying a monthly or annual fee. I wish they supported ONVIF so you could interface it into an NVR but they don't. I don't like any surveillance equipment utilizing WiFi, so when I do ring installs, I prefer to use the Ring Elite which can be hardwired over ethernet and comes with a POE injector. But yes they can be costly and their are cheaper alternatives, but pretty much Ring is the standard and most popular one in the doorbell cam market.