What do you like best?
To find, store and organize our literature, Mendeley is an excellent option! It works en several operating systems, ease to use, import/export very easy and well formatted, allows synchronization on different machines, and more features.
The annotations per each article is a keystone of the system (in my opinion). Several references are found
"on the way" without a clear idea about the content, but them are related to a particular search. Well, this information can be stored as a annotation to associate a reference with a particular search. That's amazing, it keep our mind free of remainders!
What do you dislike?
Well, is a freemium software. That's not a disadvantage, I dislike that. Also, there is no open source (in comparison with other solutions such as Zotero or Docear), but it is not bad at all.
Moreover, the graphical user interface is not "well-looked", is normal. It could be a disadvantage for exigent users, but is totally functional: effective.
Recommendations to others considering the product
You have a lot of references?
You work on several topics on your research? school?
Then Mendeley is a good option to store them, instead using single .txt files on dropbox o gdrive.
What business problems are you solving with the product? What benefits have you realized?
My main concern was about the availability of the data in everywhere. Particularly, I work using PC, desktop, phone and tablet, and the availability is crucial! Mendeley works fine on that. Actually the web version is terrific, simple but it works.
Then, to get a reference (and don't use the full memory) is an excellent tool to be used when a article/blog/scientific report should be written.