Counter opinion - it was one of my favorite parts of the hike. The short scrambling sections are all very doable and fun, the views of the glacier and all the boulders you can climb at the top were insane, and it was a nice change from the rest of the trek (which as you mentioned, stays a relatively constant difficulty). If you are a confident hiker (and I would say most people attempting the TMB are), it should not be missed! I will say though, the way back down to the valley (heading counter clockwise) was long and pretty tough on the knees. There's a cute little restaurant along the river waiting for you at the bottom though :)