Dude, as long as you are enjoying the experience of playing & learning....I would never give up on it. Playing because you love it, is far more important than any physical accomplishments or prowess on the instrument.
Regardless if it's one note or 100,000....clean or sloppy....smooth or a bit uneven....if it comes from the right place within you....it's music and it's good.
The easy things are rarely as rewarding as those that cause us fits. LOL
Quitting is all too easy in most situations and far less rewarding than having stuck with you passion. Having something as simple as a song/piece of music that YOU wrote, is often worth the trouble it takes to create it. That's the great thing about music, is that there are no hard & fast rules about creating it. You're a unique individual and the struggles that you go through, effort that you put in...is what makes your music yours. And in the end, that's the most important factor in it all.

As for your friend pointing out the flaws to you....
Unless he's being a prick about it...I would say, at least he's being upfront with you about it and not just protecting your ego/feelings. If he's using it as a way to knock you down & make himself feel better...that's a totally different story. ;)

Don