We played with 3 players. My husband (Antoine), my 9 year old son Max, and myself. We used all parts of the expansion - except for the 6 player part of course. Max was thrilled to make use of the black canoes that came with the expansion.
We found the additional paddle cards made a big difference to us during our game play. It increases both the kind and the number of options, and we also only found that we went through our paddle cards twice during the game, which is fewer times than in our previous games where we use up our paddle cards much faster.
The elk made a huge impact on the game, as several times the elk's additional paddle points made the difference between going over the falls, and helped players get their gems back to shore more quickly and at less risk.
We never made use of the beaver, which disappointed my son. It just never happened that we got the weather up to +2.
I found the whirlpool to have only a minor impact on the game. It did change our movement a bit, but didn't have a major impact on the game at any point.
For some reason, we did not find ourselves stealing any gems at all during this game. The opportunities just never seemed to come up.
In the end, Max won the game handily by collecting 4 blue gems. Antoine and I were still well behind.
We really liked this expansion, particularly the elk and the extra paddle tiles. I think we will always play with the expansion.