Fairly simple setup and good search. Team was willing to quickly feed flaws or missing features back into the development pipeline and actually get them resolved.
There are some basic design flaws such as the number of clicks it takes to download something. Users are constantly complaining that they can't just click on certain links that seem to be the way to get to the field and download, but instead have to do it from a menu icon (they always think they should just be able to click the filename or the preview icon and download)
The product was not entirely baked when we first started using it, but we were replacing Salesforce CRM content, which was so bad that anything was better.
Controls on file sharing are sufficient, but could be more granular and then would be a lot more helpful.
Embedding it in SF for Mobile use didn't really work.
SSO with SF was not true SSO, but rather a pass-thru. Ended up having to have the reps still know what their password was for this tool.
Multiple different places for different rfp, marketing or brand enablement content needing to be distributed to sales.
Content was not easily searchable--now in one place for the most part. The team managing this content is able to manage it without much technical skill, which was not the case in Salesforce.com.