This review is from the perspective of a person who skis mostly in the US and often in Austria.
Ischgl is a very large resort. As such, you can find something for everyone anytime. It has a variety of ski parks, fun runs with rolling hills, easy and not at all easy runs. The easy (what we would call green) and the intermediate (what we will call blue) are well mark. The blacks are the rest of the mountain and are not marked. You simply get off the trail and have a load of fun skiing in powder. Like in every place in Europe, if it's not sunny in the morning, you will need work extra hard in the first hours of the day because of the thin layer of ice that forms during the night and the sun didn't burn.
I am not sure why, but there is relatively a smaller percentage of snowboarders. Because of its hight, there aren't trees on the core of the mountain. You can find them on the few runs on the way down but these runs are not fun to ski on as they have too much manmade snow to accommodate the many people who get off the mountain. The recommended way to get off the mountain is via the gondola. You can lock your skis overnight for 1Euro on top of the mountain but keys are in short supply. You can also leave them in the storage room below the gondola for 3 euro. Take advantage of this great service!
The town is nestled in a narrow valley. Because of that, the town is long and narrow. The downtown area is very small and bursting at the seams with people at the apre skiing. The real estate is probably super expensive because every building's height is maximized at 4 stories while the streets are un-proportionately narrow. As a result, the town is not a 'cute European mountain town'. If you are looking for one with great snow go to any other ski town in Austria like Kaprun, Sell Am See, and more.
The ski school is terrible. Everything you know about how to run a good business in the US does not exist in Ischgl's ski school. A child who was registered with a group wanted to switch to a private lesson. The school did not credit them. An adult who signed up for a couple lessons and decided on the second day to pull out bc the ski skills of both skiers were too different, was refused the credit of 30ero. For the record, the ski instructors there give the same instructions as the ones in the US. The only difference is that they are boring as hell and communicate very little. In our group, we experienced 4 instructors and they were all like that. In short, unless you are clueless, don't bother.
I am glad I went but I wouldn't be back. The mountain is terrific but there are prettier mountains, more charming ski towns with better ski schools, cheaper accommodations, and just as good of powder in many other places in Austria. Go exploring!
