The cam info is always available so they know how i got it anyway, if i used film i put the info in the description box. And I write what it is of and where it was taken.
I don't think its important, i've gone through years at uni, teachers telling me that i'm not good at talking about my work, still i don't think its important. I love looking at photography, it bores me when people start talking to me about it when i haven't asked them too.
I used to all the time, but I also used to be more selective in what I would view. Now that I've been a part of deviant art for 2 years, and I view a lot more images, I'll only read the comments if I'm curious what the artist has to say about it. Usually though, the artwork that I'm most curious about, is done by artists that don't put a comment, which is annoying.
i include some info about the image as i feel is important. not only photos, i read descriptions of any images if available. althouh i must admit sometimes descriptions are way too long, so unless it's really interesting story or something important, i don't bother. as for the metadata, dA could not read much from my photos as i do "save for web" in PS. thing is that this option make simages lighter which is better for most people browsing the web, and also hides my exif so if someone would for any reason steal my image, i ould proove it was mine easier... although i don't think anyone would tkae my images. and i do know that there are programs to add exif to your image, and change it the way you want. if some exif data if important, then i just include that detail