I personally had a great experience with the Chen Immigration group. We worked together on my 1-140 petition (EB2 NIW): I found a team of experts who were always ready to answer my questions, and gave me support for any concern I had on the way. I never had to wait - they always responded right away, within 24 hours. Their website is very simple to use: as soon as you sign the contract, they open a private web page for you, where you can upload your documents, send messages to your lawyer, and download the revised documents. It couldn't be any easier. Also, the client packet that they provide is extremely useful and gives you all the instructions that you may need to put together the documents/forms necessary to build your case. My I-140 was approved approximately 4 months after submission and I couldn't be more satisfied with whole process. I would strongly recommend this group to anyone!!