Yes, I've used SEEP/W 2007. It's a powerful program, but you have to be very careful on your mesh, boundary conditions, and head boundary condition modeling. You can get some really neat time stepped visual results, but on the bad side you can get some really generic error messages that don't really guide you to what is going wrong. The manual is really good about discussing most things related to seepage, but falls short on guidance on error messages and their meanings. Be careful about steady state modeling when the actual conditions are transient. Good luck!
"Information is not knowledge" Albert Einstein