Against my better judgement I bought a Garmin edge 830 and after quite a few rides I can safely say it's exactly what all their other units should have been.
They've clearly (finally) significantly updated the processor as it's incredibly fast when zooming in and out of maps, is far faster at calculating routes uploaded (as in, it's done a 50 mile ride in less than 13 seconds).
The font is much cleaner and easier to read, it's got the appearance almost of a Kindle with the backlight on. The route is much cleaner on the map and had been easy to read even cycling in Spain these last few days.
The screen is also much better at reacting to touch, apparently it's much better with gloves now too though I haven't tested that yet. I also haven't tested wether rain affects it in any way, I know some had issues with the 820 with this.
My biggest issue with the 820 was battery life. With everything turned off save for gps, speed and cadence sensors my battery would run out while navigating within about 6-7 hours. 2 replacements hardly faired better.
I did a 6 hour ride yesterday in 30 degree heat with GPS and GLONASS on, speed cadence sensors connected and my phone's Bluetooth connected and I finished the ride with 84% battery life remaining.
I can't stress how much of a step up Garmin have made with this product. Imo the 800 was ok tho had fits occasionally, froze a couple of times and took ages with loading routes. The 810 my mate had seems to be a complete mess all round. The 820 was beyond frustrating with touch issues, small screen that was either hyper sensitive or lacked sensitivity depending on it's mood, slow performance on maps and loading routes and ridiculous battery life.
I'll try upload a video when I get home on Saturday of this things speed, but I'd recommend for those wanting a navigation bike computer to go in a shop and try it out, it's really very very good.