In all honesty, I am a techno-geek when it comes to gadgets for cycling. At times, I think I need them but it usually boils down to..."Hey, that's neat!...let's buy it". But the Varia Vision has been a pleasant surprise. In the past, I know I find myself looking down at the Edge unit a lot and have had a few close calls because of it. Yes...it's my justification for the VV. While it does keep my head up, the vibrating notification when using it with the rear radar is even better. I ride alone and I don't hear the radar notification from my Edge unit because I usually listen to music (yes, I can still hear the traffic). My only complaint is that the weight is noticeable and does make my cycling glasses creep down my nose. Especially when the sweat is flowing and going over irregularities on the road. There is also a noticeable weight bias on the right side (where I mounted it) of the glasses and feels like they're not sitting properly on my face. To me, these are minor inconveniences compared to the benefits. I am still experimenting with the data screens but I really like the auto scroll option set to medium instead of swiping.
If you want more info, DC Rainmaker did an excellent pre-release review.