On our way to Geirangerfjord (before starting to drive on trollstigen), we made a small detour to Eikesdalen valley and we drove there, once you get to the waterfalls you can turn around and drive back all the way or you can drive on a dirt road for 3 or so hours – views are amazing.
While in Norway, you have to try out one of the glacier hiking tours, it is a great experience and it is not as easy as it seems. I was visiting the Jostedalen national park in the center of the Sognefjord region and joined a short hike at Nigardsbreen. you walk with a small group, and with a guide, where everyone are tied to each other, you will arrive to the glacier and get the glacier hiking gear and a few pointers on how to walk on the glacier.
The walk (shortest one) is 2 hours and it is amazing, you will go inside caves, and on top f the glacier – look behind you every once in a while, there is an amazing view there as well.
In general, Flam (or Flaam, or Flåm) is a small place in Norway which i visited 2 years ago, this was one of the places i really looking forward to visit (mainly since they have such great reputation, and their site is really great, but in general, yes, it is a great place, lovely fjord and some really nice hikes and amazing views – defiantly worth the trip.
The only thing i would advise you to avoid, is the train trip, it is a really expensive trip, and the views you see while riding the trains are not really worth the price – you see all these views and more from the village itself. Yes, you will see a nice waterfall, but you will get to see thousands of these while visiting Norway. Other than that, the train (due to the fact its an historical train) is so slow so other than the money you will be spending 2 hours of precious Norway travel time.