The Tilicho Lake Trek is without doubt the most beautiful trip around Manang and a highlight of the entire Annapurna Circuit. At 4920 meters the Tilicho Lake is also excellent acclimatization before crossing the Thorung La Pass for those continuing on the Annapurna Circuit.
Technically straightforward, the path to Tilicho Lake is nevertheless more demanding than the rest of the Annapurna Circuit. It is also quite popular, and when I arrived from Manang at 2 pm the Tilicho Base Camp Hotel was full (a new hotel is under construction nearby). In that case people are offered to sleep in the dining room, as is common in the high-mountain tea houses with no alternative accommodation.
Tilicho Lake Trek two-day itinerary as walked in October 2015:
Day 1: Manang-Tilicho Base Camp Hotel (4200m)
Day 2: Tilicho Base Camp Hotel- Tilicho Lake (4920 m)-Tilicho Base Camp Hotel (lunch)-Blue Sheep Lodge, Shree Karhka (app. 4000)
Day 3: Shree Karkha-Letdar- the Annapurna Circuit
I did not find the route genuinely exposed: Though the scree-slopes look exposed from afar, and very steep looking down on them, I think that one could quite easily auto-arrest on the slope in the unlucky (and quite unlikely) event should one fall from the trail. I even met, and crossed a couple of yaks on one of the scree slopes (I took a step up on the scree slope and let the yaks pass on the trail).
However, those with fear of heights may have issues, and I saw a (very fit by the way) couple turn around.
From Tilicho Lake it is actually possible (with camping equipment) to cross straight over to Jomsom on the right side of the lake. The french mountaineer Herzog and his party arrived at the Tilicho Lake from exactly that direction when surveying the area prior to their famous first ascent of Annapurna in 1950.
It looks like the Lonely Planet Trekking in Himalaya guide has been updated in January 2016: Hopefully this has included a significant update of the Annapurna Circuit section including Tilicho Lake.