From a general user perspective it's relatively easy to use and navigate to know what work is assigned to you and the ability to leave comments in tasks as well as in document proofs. The highlight for me is that it integrates with email (Outlook for me) so that I get updates, comments, etc. in my email and can respond via email if I'm remote and don't have access to Workfront.
While it's easy to get away with the basics to hobble along, unless you are properly trained by someone in this software prior to using (or have experience with a competitor) you will miss or not understand MUCH of its functionality. I've been using it for almost a year and half, and there are still so many things I'm just now learning. So make sure you're trained properly or else you might have a steep learning curve. Or if you're satisfied with bare minimum use as a contributor and not a PM yourself, then perhaps this isn't as big of a deal.
Also, we've dealt with some annoying downtime and delayed response. We've had almost full workdays where it is "down" and unusable (NOT on a scheduled maintenance day). There have also been days where its update system doesn't notify people for hours after your comment or request, so you have sit in the program and hit refresh constantly if that happens, which can be annoying. It doesn't happen frequently, more like once a quarter.
If you don't have experience using this or a similar product, do some training and research. It's a very complex program with lots of capabilities that are not readily apparent to a first time user.
Workfront is the software our company uses for project management. Our PMs manage our instance while individual contributors such as myself comment, approve, and do timesheets. We've benefitted from having our projects and timesheets in the same place--it makes it much easier to keep track of hours for our agency.