Peoples' experiences differ. There are probably many many happy 800 users. Remember, you tend only ever to hear the complaints.
And, to be fair, with any new development you will get teething problems. I seem to recall it happen on the 305 then 705, probably 500 too. In an ideal world, you would give a new unit a thorough test (and I'm sure Garmin do attempt this) but with the best will in the world, it's not always possible to replicate the real world environment in testing... that said, maybe Garmin are slack in this area
Certainly, from my perspective, I'd anticipate there to be teething problems with any new product - and may even hang fire purchasing until they've been identified/rectified. Maybe the fact that I consider this to be particularly true of Garmin Edge units should perhaps make me question my own opinions! Because I do think, in all honesty, they are pretty excellent bits of kit all things considered.