DomainState has been around for almost as long as DNForum.com. Their whois indicates their domain was first registered in February 2002. Since then, they have been shoulder to shoulder with DNForum.com in most respects.
What sets this forum apart from DNForum is the fact that DomainState is a free forum. There is no tiered membership structure – everyone is created equal. What's more, this forum has provided domainers with some awesome domaining tools, like the All-in-one whois tool, used by many domainers today. The multiple who is checker is a free tool. You can download both at their tools section for free.
DomainState also provides its visitors with a plethora of free goodies including links to various free overture tools, ppc calculator tools and a lot more. This is something DNForum should seriously look into.
This forum experienced a huge upsurge in traffic when DNForum.com restructured into a paid membership forum. This upsurge in revenue has probably explained the reason they have been able to develop so much free software.
On the down side, their lack of an intuitive interface and a boring, old design, really drags a new visitor down. They would probably benefit from a redesign which would definitely impact on the number of new signups. This has an impact on their domain marketplace as well. They definitely rank lower than either of their main competitors in terms of the number of offers you can receive for your domains, and the quick response times for appraisals.
The lack of a proper design and intuitive interface probably explains the lack of the sense of community at DomainState. There is no forum money and no live chat or auctions.
Overall, they rank as a mid to high quality domain marketplace that could be great with a few minor improvements. If you want to make a quick sale, I would recommend NamePros.com or DNForum.com over them at this time.