From basecamp at ~16,500, the climb begins with a series of switchback traverses past high camp at ~18,000ft on a relatively well packed trail. There is then a short section of 3rd class scrambling up narrow gullies which begins just above high camp, and there were occasional 4th class moves, but was pretty much hiking on stable rock for the majority of the approach.
Eventually, well above high camp you reach a very short ridge traverse of a few hundred feet before you hit glacier, snow, and hard pakced alpine ice which probably varies in its initial altitude depending on the season. From here, you can tie in and alpine simul-climb up to 5800m (~19,000ft) crossing crevasses along the way. At this point, you reach a an open plateau and there is a tall steep headwall ~1000ft of moderate snow that guides will typically put fixed lines on to gain the false summit and then top out. In recent years, a large crevasse has formed in the headwall many people around, but it can be negotiated.
If basecamp is near the latrines, you continue past them about 1/2 a mile circling around the southern edge of Island peak. If you go far enough to see Lhotse, you have gone too far and passed the trail. It is several hundred feet back toward basecamp that you start your climb. The trail is viewable as a series of switchbacks working up the south face. The glacier and summit will not be viewable this close to the base of the peak.
No rock pro is necessary. Long ice screws and maybe a picket or two are helpful for building snow anchors for the final pitch. However, you could probably safely solo it if you are comfortable with the lack of oxygen.