Went solo on this trip the last week in September in 9 days/8 nights. One needs a permit and there is an easy system to sign up on-line either through a lottery system in March or there are walk-up intermarry possibilities if one has a flexible schedule. Also, routes can either be clock-wise or counter clock-wise in layout. The hike could be comfortably be done in 7 days/6 nights from a mileage perspective. I would rate this as 'hard' but not that 'difficult' in that there is +/- 25,000 ft. of elevation gain and loss for the whole hike, 2k-3K per day on average. It is hard as there is so much up and down. Hiking poles for me were a must. It is not difficult in that it is, during the summer months, a heavily traveled trek and the trails are generally well maintained and easy to follow forest paths. Each day you at going up and down at least one major 2K+ foot section between camps. With side-trips, the 93- 96 mile trek easily ends up over 100+ miles. I took the alternative 'Spray' trail in the northwest as this route is higher up, with closer views of the mountain. There are mountain goats, elk, dear and bear and, the ever present marmots. The weather cooperated, for the most part - 4 days of sunshine, 3 days of overcast, 1 day of rain and 1 day of snow (at 6,000 ft.). The temperature was in the 50s during the day which made for excellent hiking conditions, without overheating. There were no bugs and few people in the camp sites in late September. One is rewarded throughout with spectacular views of the mountain, hills, valleys and rivers as well as different scenery on each day as one heads through different sections and climate zones. In late September, the colors of the bushes change to fiery reds, oranges, yellows and purples - all providing a stark contrast to the bare mountain terrain they grow on. The Wonderland Trail takes one through barren outcrops, subalpine meadows, old growth forests, 'burned' out sections that are regenerating, talus fields and, of course, raging glacial river valleys which leave their silty/rocky deposits below. It is 'hard' because of the elevation gains and losses. All bridges were in place and markers in riverbeds were easy to spot as one navigated low lying sections. I enjoyed the campsites as they all have backcountry privies that are convenient and bear poles for your food/trash at night. In late September, there are few that you are sharing with. One of the pluses for this type of hike is that in each corner of the park, there are cache points to pre-stage food if you choose not to carry it all with you. Further, all campsites, save one, had stream, lake or other water sources near by so water for cooking and drinking was not a problem. Few trails of this length are as well laid out and maintained, with spectacular scenery, and this is the grand daddy of them all. Take the time - it is worth it.