The team at vss has been great to work with in terms of solving our problems, they are very responsive whenever there's an issue or question that arises during their project management process as well! I haven't found anything about working w/ them yet but it would be nice if we had more options for customizing some aspects (ease-of use) such as password resetting rather than having all accounts locked out until someone from support logs into your account via email address - not ideal solution considering how many employees have access & passwords stored anywhere other then within one central place like lastpass etc..
Great experience so far though!! We've solved almost every problem they came across while building us this application which was used internally by over 500 people daily along side Salesforce CRM system using sales force API integration.