My husband and I went to Trolltunga in mid-July, on a Friday. We camped at the side of the road in a tent up the hill from Skjeggedal because the campsites in/near town were already full by 8:30 PM. Just a heads-up that once you get to the town there are not many places at the side of the road to camp.
There is parking at the beginning of the trail that you can pay for at a meter with a credit card, and we paid 100 NOK for 12 hours (but you can pay different amounts for different lengths of time). We got to the parking lot around 7:00 AM and there were maybe 4 other cars there, but we took our time eating breakfast/making sandwiches for the trip and by about 7:30 quite a few other cars started showing up and the parking lot started to fill up. There are people monitoring the parking every now and then because a woman on a bike came by to ask us to move our car to make more space for others. There are two free toilets next to the parking lot but when there are many people there the line-ups become long.
The trail itself is 11 km to the rock and 11 km back, a total of 22 km round trip (although my husband tracked our hike on his phone and it was closer to about 25 km actual walking distance if you include the switchbacks). It is suggested that the hike will take a total of 8-10 hours, so bring plenty of food and water. We started our climb at around 8:00 AM and the foot traffic was fairly light at first. Some of the reviews I read prior to the trip were a bit misleading about the difficulty of the hike... If you are an experienced hiker than the hike is tricky but manageable; however, I am not an "experienced" mountain hiker (i.e. I have done hikes but mainly on more level terrain or mountains that have fairly level trails) and I found the trail to be quite difficult. The first 1 km was a fairly steep upward climb with a very rough, dry trail consisting of rounded and jagged rock which, at the 1 km mark turned into pure mud which was impossible to hike around. Definitely make sure to wear good hiking shoes, as you will want good grip and they are bound to get covered in mud and water.
The trail starts to level out after a little over 1 km, although the thing that some of the other reviews left out was that from about 2.5 - 3.5 km the trail becomes steep again with more mud. I had to stop several times to take a short break, although the more experienced hikers seemed to be okay. Just a note that there are no toilets along the trail or at the rock, so bring toilet paper (and finding a spot to go where no one can see you is tricky). At about 5.5 km there is an emergency shelter (a tiny cabin), but only to be used for an actual emergency (e.g. stranded in a snowstorm). We were able to refill our water bottles with clean water from the many of the streams/waterfalls along the trail.
The scenery on the way to the rock is breathtaking in itself, and the view at Trolltunga is spectacular. Many more experienced hikers had passed us on the way there, so by the time we got to the rock at around 1:30 PM there were maybe 20 other people there, with more on the way as we left around 2:00 PM. We did have to take turns going out on the rock, but the line-up was maybe about 5 people long at most and people were really good about giving people time and offering to take group photos for each other (there is not enough time to set up a camera timer and get to the rock in time).
I will be honest, I found the trip back more difficult and it took a bit longer because it is mostly downhill and was hard on my knees. The last 1 km was tricky because it was even muddier than before due to all of the foot traffic from the morning, and the dry areas were treacherous because little pebbles made the dry areas slippery. Overall, my husband and I took just over 12 hours to hike, although I think the more experienced hikers took 8-10 as suggested and found the trip back faster. We were lucky that our car did not get ticketed for being overtime. The parking lot was very busy when we returned, so there was a line-up at the toilets (about 5 people).
Overall, I will be honest: there were times when I was incredibly sore and regretting going (more so on the way back), but it was totally worth it for the experience!!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.