I am a microstock contributor. I create and sell mostly vector images. Some time ago i was intensively looking for a new profitable agencies where i could upload my vector works. One day in one microstocker's blog i've found good responses about Graphicriver. I've never heard about this agency before so i didn't expect much from it, but anyway i've decided to try it. Now it's about a year when i am contributor in this site and i must say i'm really happy to be there Let me share my experience with it:

http://graphicriver.net/?ref=vecart - agency that belongs to Envato group, together with photodune.net, videohive.net, themeforest.net and other sites.

Advantages:

Good sales - probably the biggest and main advantage of this site. For me it is strong no.2 earner. Only Shutterstock does better for me.
Steady sales - different microstock agencies has different search engines. In this agency number of sales rises very significantly for several days after new works are uploaded. After that it falls down a bit but still remain good. Even if new works aren't uploaded for a long time - sales doesn't drop dramatically and remains steady.
50 USD payout minimum- small payout minumum is always advantage.
Good contributor support - some time ago i had some questions about using Graphicriver, so i wrote letters to it's staff. Staff was very helpful, polite and answered quickly.
Different format works - You can submit there not only vector illustrations, but also PSD works, also logos, print templates, t-shirt designs etc.
Great stats displaying - i like thorough sales and referral stats and anyway contributor account is easy and comfortable to use.

Disadvantages:

Time-consuming file submitting process - For vectors (i don't know how for other formats) You have to prepare three different files for each design: 1)  80x80 px size JPEG thumbnail image 2) 590 px width size JPEG preview image 3) zipped file with high resolution JPEG file, vector file, and some additional formats (optional) inside.
Preparing these files requires additional efforts and time.
High rejection rate - i don't know how about other contributors, but i get a lot of rejections there - more than in other agencies. Most common reason for files rejection - design didn't fit Graphicriver's high quality standarts.

Other features:

File pricing - File price is set by Graphicriver's reviewer. It is often 2-5 USD for RF vector work zip. Sometimes this price may be different. I get 33 percent earnings per sale. This percentage also depends on how many sales contributor made overall.

So i can conclude that graphicriver has it pros and cons, but anyway it is very professional agency with big potential and it is worth to try.
My link:

http://graphicriver.net/?ref=vecart

If some of other contributors sell works here, it would be nice to hear their opinion

Ditto, pricing a p*ss take, upload process a nightmare, review process random (particularly annoying when you have to jump through hoops preparing your files), and a crappy ethos at the site re. copyright violations (do a search on this forum)
Really not worth undercutting yourself uploading to these jokers.