Your visual designer has created a unique UI concept, and most importantly, it seems to fit the client's needs, but how do you promote this UI to the client? I've run into this several times since many of the common UI paradigms that folks are comfortable with are out the window...it's tough to convince and push a new concept that seems foreign to some. Be sure that you get the client on a phone call, at least, and allow plenty of time to review the concepts visually over some interactive web tool. More importantly, this UI concept design review will surface vital errors in the design. Engage the entire team and make good use of an hour slot. Don’t depart the meeting without an internal review of the outcome to assure that the design moves forward correctly and the next set of mockups are delivered quickly to avoid losing the momentum of that heated meeting. Be sure to continue iterating on them via email immediately. The PM's goal is to get locked on a design concept.
On the flip side, it’s vital to assure that the developers can pull off the design given the estimate that they provided for the project. If not, your budget is in jeopardy, assuming you're doing a fixed bid project with an estimated cost structure from the developers. Going too deep in your design, without a team lead and/or integrator validating the design along the way, is a critical error for a PM on this technology. Ideally, the visual designer should be free to explore UI, and the client should reel in the team if it’s gone too far. Just don’t bite off too much is my point. Don't forget about your QA team, too. They need to be just as engaged. It keeps the PM's job minimal here, too, since the test plan is fed from this information and the handoff is self evident.