I used them for about 3000 miles of commuting on the country lanes to and from work, got sick of the repetitive punctures in normal tyres.
one thing i would say is that they come with a “coating” this takes about 300 miles to come off, after that the grip greatly improves, until then grip is horrible (the coating has a slight metallic fleck to it).
So if your friend does buy them, tell him to wear them in first.
They are not perfect, it is a solid tyre after all, but they ride a lot better than you would think once worn in.
Postives:
Great for commuting as worry free, don’t have to carry tubes, pump, patch kit etc.
Ride like a hard pumped Gatorskin and better than something like a really heavy Marathon or similar.
After 3000 miles they didn’t have many signs of wear.
Negatives:
A right git to fit.
Grip rubbish for first 300-400 miles especially in the wet (watch painted lines)
As they are solid, they were fine for 28 mile each way commute, but if rides got much longer then you tend to tire more quickly as you feel more vibration through hands.