It's alive and well and membership is free but with a limit to numbers of uploads. A subscription allows unlimited uploads. I use it for the following reasons....
For archiving information and photographs on specific subjects.
Each photograph includes descriptions and links to further information.
Flickr is an excellent resource for information.
Viewers can zoom into a photograph to see detail.
Because of that, viewers can 'walk around' a photo, such as a church interior, providing the resolution is good enough.
My subjects are mainly churches, classic vehicles and steam locomotives from my part of the world. Other like-minded individuals do the same for their patch, particularly in relation to churches. Why do we do this? Because they'll probably be gone within 10 to 20 years due to lack of interest and / or intervention by progressives who'll want to ban anything old. So if we don't archive such things, all we'll have will be memories or blurred photos devoid of connection to time, place or subject.
I'm limited in the numbers of photos I can show because in my opinion, the description takes precedence over the photo, even though I try to take as much care as I can with the latter. However, I have noticed a few things over the three years I've been using Flickr......
A lot of comments are “Good capture”, “nice capture” and “nice shot”. A lot of this is down to 'groups' where members are obliged or even required to 'comment' on other members' photographs.
Interesting comments tend to be amongst users with a specific interest. For instance, discussion about vintage cars, steam locomotives, old buildings etc. Not so much about each photograph, more about the subject.
Resolution is limited. 60 mp perhaps? I posted a 100 mp picture once and the detail wasn't as sharp on Flickr as the original.
Difference in resolution across camera brands. You need to check this out yourself but I find it very interesting.
It's difficult to find a photograph using a search engine such as Google. You have to open Flickr and then search within that and remembering to sort ('relevant', 'date taken' picklist).
The 'user experience' isn't exactly intuitive or straightforward but once you remember how to do things, it's OK. When you upload photographs, messages like “milking butterflies” and “frobulating widgets” come up for a fraction of a second which partly alleviate the downsides.