Don't even think that the interface changes with 10, it's basically the exact same with 12, so it's not easier to use or anything. Not being very knowledgeable about the exact details, I prefer 12 because you can zoom in/out your masks without having to re-do them. If people are saying 10 is better, it is for reasons like less crashes, less problems/bugs and stuff like that, which I am not particulary concerned about.
If your friend is so adamant about using 10, feel free to, I wouldn't know since I am noob at programming/pc knowledge in general. Tbh, at this time I have a 32-bit pc and I use 10 solely because the torrent I have for 12 was for 64-bit and I can't say I see much difference, they feel like the exact same program to me.