I think it comes down to 'how you use it' and 'what you want from it'.  The interface could be better I agree, but looking at Deviant Art and others, they have their issues too, yet they are much much smaller in terms of content.  Flickr still offers a great deal over the alternatives.
Personally, I love it.  It allows me to share my photos among fellow photographers/friends.  There are specialist groups which no other online photo hosting even comes close to offering.  I bought a panoramic pinhole 120 Holga and needed some help; I got it within minutes from a group for fans of this camera.  At the end of the day; don't post in stupid groups like 'post 1, comment on 4 others'; as they are purely for people wanting an ego boost.  Why should they bother you?  Instead, find some good groups, find some good contacts and build your own great little community.  I have made some good friends who I have actually met in person.  
Another thing I have found it great for, is finding new photo locations.  For example, I looked up Windmills on Flickr, it led me to Chesterton Windmill, I found many shots on Flickr, within a minute I had found one where someone had entered GPS details (clicking 'map', next to the EXIF), and voila entered them into my Tom Tom (longitude/latitude) ... it took me to the exact spot.  I have done this time and time again.
I have had a couple of things published too, which would not have happened with my own website.  I also don't want to promote myself as a 'Photographer' as I see what I do as a hobby, I also do not see myself good enough to tag that to the end of my name.  Flickr keeps it relaxed for me.
