> Among its terms are "[Y]ou must give appropriate credit, provide a link to the license, and indicate if changes were made.
> I did not see any link to the license or indication of whether changes were made.
It doesn't say you must indicate whether changes were made. It says you must indicate if changes were made, which leaves the case of "no changes" ambiguous.
And what are "changes"? Does a minor crop or sharpening constitute a change? (Or, more precisely, a remix, transform, or build upon.)
Leaving aside whether they are free licenses and whether that matters, my issue with the CC variants is that both NoDerivs and (especially) Non-Commercial are nearly impossible to define in the general case and therefore cannot be safely relied upon as a grant of permission if you're being legally conservative.
I think No-Derivs is only acceptable for interviews or speeches that are a statement of the author's views (allowing derivatives would not make sense). And No-Commercial is just nonsense and people shouldn't use it.
Unfortunately, NC is one of those things that is intuitively appealing to a lot of people--"I'm happy to give my stuff away for free but I don't want someone else to make money off of it". But it breaks down with essentially any non-trivial use.
Yes, using a photo off flickr as a screensaver on my home computer is clearly non-commercial but, really, who cares if that usage is properly licensed or not. Pretty much any substantive use could be argued to be commercial in some way, shape, or form.
> I did not see any link to the license or indication of whether changes were made.
It doesn't say you must indicate whether changes were made. It says you must indicate if changes were made, which leaves the case of "no changes" ambiguous.