I think that waiting for more than one review is no bad idea for anything!
For example I remember he mentioned some issues with his pre-production version that HP said would be sorted on production version (although exactly what they were I'd have to re-watch because I can't remember). He seems to be taking them at their word these things will be fixed when recommending to pre-order it. Even beyond that we all have different head shapes, eye positions, preferences etc and it's probably good to get as broad a perspective on a new headset as possible.
All that said, I decided to pre-order mostly because it lines up with my birthday at the end of September so would be nice to get one for then... If in the meantime some other reviewers get their hands on units and point out some problems that are a deal breaker, the pre-order can always be cancelled. Failing that, if it arrives and isn't up to snuff then it can always be returned! My suspicion is that HP should be able to apply the lessons from the G1 here and produce a better product as they aren't going for anything crazy and are really just iterating upon the base of the G1. My understanding is they fixed quite a few of the major problems in the first batch of the G1 with an updated v2 G1, so here's hoping they've been taking notes and can avoid that mess this time around.