we played this game yesterday for the first time, 4 players and 1 hour and a half to end the game, because the last one card was the very difficult green card.
1 hour and a half is too many time for this kind of games for us.
I hope you played this game faster than us...
It can go long, but that does depend on the group and number of players. I played the other night with 2 of my sons, and we got 2 complete rounds played in about 45 minutes. At least with us, if someone is way behind, they'll take the last card just to end it rather than try to claw their way back by stealing cards from someone ahead of them.
I agree, though, that with too many players the likelihood of going long increases, if for no other reason than it's harder to get a complete set with so much competition for the same cards.