Xbox One purchase is beginning to feel imminent here. 
Indeed, most games have some initial issues nowadays. I surely hope early access, or day 0 as you call it, will be treated with the same amount of care and support as official release dates usually do (day 1 patches and such).
I mean I'm sure forza will have the odd bug here or there, most games do but I haven't heard anything of some obscenely large day one patch to fix things that shouldn't be broken in a game that's just gone gold. So we can at least be semi confident that the game will be playable from day 0..
Indeed, most games have some initial issues nowadays. I surely hope early access, or day 0 as you call it, will be treated with the same amount of care and support as official release dates usually do (day 1 patches and such).