Fieldglass does a good job of displaying the jobs that are open, and allows for vendors to quickly determine the status of the jobs, the location, posting dates, and how many candidates you have submitted for each one.
Fieldglass does allow some filtering and search capabilities. When you get to a large number of jobs on which you are working, that is invaluable in keeping organized. Many other VMSs do not do a good job of this.
The submittal process, of attaching a candidate to a specific job, is fairly short and straightforward. That's important because it saves time. Many VMSs take forever to get a candidate through, and are not intuitive at all. Fieldglass is better than most in that regard.
The simple display and way you navigate the jobs page is not very intuitive. There could be better information displayed than what is there, and it doesn't always make sense in how you move from one page to another.
I really don't like the requirement of the last 5 digits of a candidate's social security number for the "Security ID." Some candidates are reluctant to give that out, when paired with their birth day (also required). I'm not sure why this couldn't be a different piece of information - last 5 of the primary phone number, for example.
Some of the field are not well-defined. For example. there is a Resume field, then an Attachments field. And the rate section isn't 100% clear, especially when entering overtime rates or discounted rates.