From my very limited experience, I'd say the 30 minutes per player are about right. Of course the first plays may take a bit longer since people have to get to know the different actions. The many cards are not a big factor, since the number actually used per game is rather small (14 in your hand + those played by other players).

One player: excellent!

I can normally play the solo game in 30-45 minutes. Probably quicker once I dont have to think so much about my turns. Multiplayer, it is about 30 mins per player, but quicker once people have experience with it and spend less time thinking about what they need to do next.

I found the 30 minutes per player estimate was a good one, but add another 15 minutes to the game for everyone to translate their cards assuming: (a) not all players are fluent in German, (b) but all players have a copy of the translated appendix.

If you have fewer copies of the appendix then there are players, the translation will take longer.

I'd also add 30 minutes to the game length the first time you play.

Thus for 3 players, expect the first game to take about 2 hours.

Thanks for answers.
And is the solo variant that good ??

First game, five players, four newbies, took around three hours not counting a 45-min or so rules explanation. Keep in mind this was late at night at a gaming convention with alot of distractions (people milling about, getting up to take breaks, etc.) One you learn all the cards I would assume it would go a bit faster. However, while it should go faster in the early turns, in the later turns when there's alot of pressure to get stuff done, I could see some "analysis paralysis" in determining the order
of taking certain actions as one tries to figure out what each opponent is likely to take and plan accordingly.

Haven't tried it solo (I don't own the game) but seems it would be about as exciting as solo Roads and Boats -- i.e., not very. If you don't have the game in the language of all players or with post-ups, looking up the card translations would add significantly to the playing time.