If you like ice cragging, this is the place to head for. Here you will find the hardest moves at Rjukan and this is the place where the famous rock (ice?) stars establish their test-pieces. The area has an easy approach and some of the routes are bolted, allowing you to climb at your limit in relative safety. Don't get complacent though as there are always lots of things to consider when you are ice climbing. The area also has quite a few gentler waterfalls to even things up a little bit including a few amenable free-hanging icicles and some wide and slabby waterfalls. None of the routes are more than one pitch long (usually around 10-30m) and it is possible to tick quite a few in a day - although the area can get crowded, especially at weekends.
There are a number of possibilities beyond those described in the Rockfax guide.
Note that the bolted routes in the Fission Bowl, to the left of 'Fission' were bolted as sport routes (by Rein Leindal), not as drytooling routes.
The crag is a short walk from the large carparks just beyond the tunnel.