My company is in the final process of training everyone for the LNAV/VNAV approaches. I recently flew one in VFR to JFKs 22L. The non-flying pilot stays in raw data to make sure we stay on course. The GPS/FMS system has done very well. I'm not fond of the pitch down at VNAV path intercept however. Otherwise, VNAV seems to do a great job determining a glidepath that complies with all of the altitude restrictions on the approach. Additionally, there is no pitch change required at autopilot disconnect. It is trimmed up and all set. As previous replies above have said, raw data back-up is probably best for the moment.