If you're talking about following the red line on the map, which was drawn by yours truly, the terrain along the route up to the notch east of the summit was mostly easy talus with a short section of easy knife ridge. At the notch ("UO") you need to get on the glacier for the easiest route to the summit from the north or northeast. Access to the glacier from the notch is not difficult even in late season. The south and east sides of the summit are cliffy class 5.
From what I remember, the area from the "UO" notch down to the southern drainage are continuous talus. I didn't notice any significant cliffs. However, the south side of the summit of Lyell is surrounded by cliffs.
Last year, I hiked along the SHR from 1000 Island and headed over a pass just east of Ansel Adams to the lake you are mentioning (WL 11311T) and back over Rodger's Pass. The hike up from the lake to the glacier did not seem too bad from below. Nice, quiet area.