I have just dealt with the crones of the bog, and I want the game to go on forever.

If you went straight from Vizima to Velen then you're barely started as far as I can tell. At least I have gotten quite a lot further than that and I just got to Skellige.

It's pretty damn big. :) I'm at level 27 right now and my best estimate is that I'm about 75-80% done the game roughly. I've heard some people have finished it as early as level 35. I'm a completionist though and all things considered I suspect I'll be at a higher level than that when I finish. You haven't even started the game yet... :)

Hello.

To be honest, i do most of side quests, don't play gwynt (will do on next playthrough), and i'm nearing the end of the game at 75 hours of playtime on normal difficulty.

That's a damn lot ! This game is money well spent. Thank you CD Projekt !

Excellent.

How big it is? If we measure in hours, no gwent whatsoever (except one intro match in White Orchard), it took me around 200 hours to complete game, including clearing all visible question marks (and finding few new), and completing all quests I could find. In terms of kilometres, I really not sure how to measure that up.

Hmmmm makes you wonder ...
CDPR said W3 is bigger than skyrim by 25% yet Skellige is, like, half water !
Game is big but I think regarding content Velen is bigger so look at your map and roughly look how much u got left, half of it is the amount of content in skellige

My playthrough took 200 hours exactly (steam counter) and I hate that it is over. Really looking forward to expansions and second playthrough.