WhatsApp now shows you when your message have been read

WhatsApp rolled out a new feature that may seem small but can actually make a big difference in communicating with others through the app. Users will now see double-check marks lighting up in blue after their message is read by the recipient. You probably think this is old news; but it’s not.
Ever got angry at one of your friends for not replying to your WhatsApp message even though you could clearly see the double-check mark next to your sent messages? Now is a good time to apologize to that friend.
Many users thought the double-check mark means the other user has read the message when in fact it only indicates he or she has only received it.
It might be useful to remind you that the single check mark next to any message you send tells you the message has reached WhatsApp’s servers only.
WhatsApp’s new feature can be useful, but there’s more to it than just the blue double-check mark. If you press on any message you sent, you will find a new option: info. Click on it and a screen showing you activity details related to your message such as the time of delivery and time of reading.
I’m personally not excited about the new option, to say the least, as I don’t want anyone to use such details against me. It would have been great if this was treated in the same way the "Last seen" feature is treated, i.e., keep it optional.
As for groups, the blue double-check marks will appear next to your message only when everyone in the group has read it but you can alternatively press on your message and go to "info" to see who read it and who didn’t.
WhatsApp’s new feature is not an update so you don’t have to update your app to see these changes.
What do you think of WhatsApp’s new read notification? useful or intrusive?