Specific scenarios where Blackbaud DonorCentral is well suited are definitely in regards to our Development team. They can quickly update our constituent's memberships and keep our communications team in the loop on current member emails and those who are in need or renewals. It also helps with their development and fundraising events. They are keeping track of the highest donors and those big prospective donors for future events. Scenarios, where it is less appropriate, are definitely in my meetings department. It does not sync with our registration database for conferences, so we have to do double work verifying if they are members or not.
I gave it a low rating because response times are slow. It does have multiple ways to reach support, but it usually takes a while before you "get in front" of the person you need to fix your issue. Also, problems seem to happen a lot, so it makes the process more frustrating.
I do not know of any other alternatives, as I do not work in the development department. Our Development team would have sourced alternatives to settle on this one.