It seems this is a must do I you're around Hanoi. 2 of us went and were joined with about 10 others in our group. The coah there was nice, but we did stop at a very touristy/pushy cafe/local goods centre, which was nice and sold traditional things, but it wasn't necessary and after a while pushy shop keepers get a bit hmm. But we only stopped for 25 mins before carrying on! We got there on a bad day- crazy crazy rain! The boat ride was nice, albeit a tad wet. But I'm sure on a warm, clear day it would have been fab! The women row about 6/7 people up the river- they're very strong! We got there and had a buffet style lunch, which was nice enough- there were meat, vegetarian and fish dishes so it suited everyone! After that we walked up to the top (the chairlift was out of Order....) but I'm gla we did because I can't imagine how time would fill if you didn't walk up. It is steps though, and uphill for a good 45 mins.
The top is nice and it's lovely to get there, and so is the boatride. But it's a good 2.5 hours drive from Hanoi and left my boyfriend and I wondering whether it was worth it. But like I said, horrendous rain!