There are some (bad) reviews on GOOG:

http://www.eslteachersboard.com/cgi-bin/review/index.pl?read=46599

http://forums.eslcafe.com/job/viewtopic.php?t=97232

If you still decide to join, make sure you're working with Z visa/Residence permit, or legally.

If you have RP, you can seek Gov. help (SAFEA = Foreign Expert Bureau), if Co. doesn't respect Contract. 

Search here for 'SAFEA" to get post about SAFEA's address and contact no. in your city.

You can walk away from the Contract, and keep your RP with SAFEA's help, if Co. doesn't respect Contract.

You're going to get paid little to nothing, never have a workings visa, and basically be a puppet for them. Do not sign with them. 

I have a co-worker who used to work for them.  Basically the school paid Buckland 10,000 RMB a month and Buckland paid her 4000 RMB a month.  Oh and the school paid Buckland a finder's fee.  If you try to quit, they will do anything in their power to get as much money from you as they can.  They also will be petty when and difficult when you try to get a new job with a new school.  You are better off working directly with a school and never use a third party contractor.   

There is a blogger who wrote a fair bit about them. Seemed a positive experience to me:

http://www.twoamericansinchina.com/page/31

You should be able to contact them on their FB page for direct info and feedback.

It's interesting how a low count poster asks a question that is answered negatively by other low count posters. 

I worked for them, and they were a pretty decent employer in my experience. Low to average salary but also really low teaching hours and plenty of unofficial holidays in public and private schools- so plenty of time  to travel and do private tuition. The downsides are that you can end up teaching in the middle of nowhere, as they tend to specialise in finding teachers for schools in quite small cities. But you can specify where you want to teach, and as long as you play hard-ball with them, you can find somewhere decent. I wanted to go to Chengdu, for example, where they have a number of contracts, but the school pulled out at the last minute and they wanted to send me to a school in a city near Xi'an. I turned this down though, said I wanted to teach somewhere nicer, and ended up with a really nice job in a middle school in Hainan. They have a pretty helpful and open facebook group if you want more opinions on them.

Depends what sort of experience you want in China- but they stick to the contracts, offer good support , make sure your school doesn't mess you around and you'll have a lot of free-time to make money from private lessons etc.  If you have an idea of where you want to be placed though, specify that, and stick to your position.