Well if you're interested, here are some things I've gathered from his stories.
The trek was something like 12-14 days long, I think it starts from Lukla? Whatever that place is with the high-altitude airport. There's a relatively small mountain you can reach from the base camp which was the final goal of their trip, 5100-5200 meters high.
Altitude sickness has to be the worst part. You should really prepare for it as best as you can; try to make some trips to something like 3000m or so in your area. Certainly not Mont Blanc
but whatever you can find, in order to get used to it. My friend experienced a lot of the bad stuff - headaches, lack of appetite, lack of sleep, nausea, and so on. He lost something like 9kgs in that time, from 90 to 81kgs. They've had to force themselves to eat Snickers and drink Coke to get enough calories to go on.
You also can't wash yourself and it's pretty hard. He said he paid an incredible sum of money for a single cold shower at something like 4000m and yet it was worth it.
The cold is also very bad, there are some places to sleep along the route but mostly it's literally a wooden house that the wind blows through all the time. He slept in his bag with a flask to urinate into, because going out was so bad.
Then again he said the views were worth it, no question
He also wasn't as prepared, they only took a few treks into Austria at 2000+m high places before but that was all. He's gotten a lot tougher and leaner in the past years (nowadays he routinely goes on 20+km runs in the hills around Budapest) so I'm quite sure he'd do a lot better in his current condition. Still, it's probably quite a mental challenge to go on; most of their party did not even make it to the base camp...
I sometimes also feel like it'd be a real experience but I think I'm now getting a bit too old for this at 37. My endurance has never really been that good - I did ran a half-marathon some years ago and did 28kms in another run in two parts, but it was really painful and I'm more focused on strength training nowadays anyway. Still, who knows...