Still the VNAV might need more polishing.
Rather than a bug report, I'll post some of my "feeling" with VNAV here:

1.When initiating a desced, the actually pitch will lag behind VNAV path, both from T/D or from FAF when doing approach. seems the path calculation didn't have the "cruve connection" actual aircraft needed to follow, like the LNAV's one.

2.In general, PATH seems to shallow above FL100 around 300kts and too steep below 240k/FL100. The SPD mode will kick in frequently above FL200, and sometimes it enter THR HLD before IDLE out, use almost half throttle to keep aircraft on the PATH, but after 240/FL100, I'll always need at least a half of speedbrake to keep my aircraft on path with IDLE thrust.

3. When there is more "hard" SPD/ALT restrictions on decend path, FMC seems glitch out. If there is only one or two, all seems fine, but if more, I weither get a large jump when passing some (even non-restrictied) waypoints, or the VNAV path itself just jump up and down like a mad when descending.