What do you think of my friend's singing voice?

This is the second time you have asked about this recording. It is fine for an interesting hobby. It isn't fine for someone who would like to do this seriously. The piano playing isn't good enough for that and the singing needs years and years of lessons to improve the tone the phrasing and to improve the dynamic range. If you aren't prepared to have offline singing lessons and piano lessons you will need to think of something else to be 'going places.'

This may not be what you want to hear, but it really was unexceptional. Lots and lots of people can do what you have just done and lots of them can do it a lot better than you can.

You can't ' go places' unless you are the best of the best. You may be the best in your street or even your part of town, but you need to be the best in your state. At the moment your singing is great for a hobby singer, but it isn't even close to the skill levels needed to be a professional singer. These skills are what you learn during the several years of offline singing lessons.

its good but quite flat at some places and is also frequently fluctuating..

can u rate the voice in these videos?

http://www.youtube.com/watch?v=WGoMVRM1DXE

http://www.youtube.com/watch?v=RpGP1iAJEoQ