I'm a self taught guitarist(if you don't count Rocksmith 2014) who plays rhythm guitar only as a hobby. I always get tongue tied when someone asks me "are you a beginner?" because I don't know the answer to that myself. I can play an easy song and some intermediate level song of a particular style, like for example I can play a tune like Would - Alice in chains & also something like Disposable Heroes - Metallica, but when i play/learn something like a trivium song or say a country tune i suddenly become a beginner. So how does one assess and categorize himself, are there any prerequisites/techniques under each category ? what is the criterion for this ?
Not the easiest of questions to try to answer, but - exams have always been a way to determine this kind of level. In essence, someone on, say, grade V on any instrument could be construed as as advanced as another who has grade V. Especially if it's on the same instrument. However, there are various different styles of guitar, and playing.This has been addressed by exam boards to some degree. ABRSM and Trinity hold exams for classical; Rockschool for electric, and also other 'band' instruments; and RGT for electric, rock, classical, acoustic, bass, and just coming up - ukelele ! Other parts of the world will have their own exams. (These take place in a lot of countries).
This is only one way to establish one's level, but it is recognised throughout a lot of the world. Obviously, it's not the only way, but it does provide a good idea to those who know the systems. Going through also tends to make one a more rounded player.
A guy I know was first met during one such exam. "I've played for years, and I'm doing my first exam -grade VIII" he said. He failed spectacularly, but fair play, he's been back every year since, now up to grade VII on - electric, acoustic, and classical, along with theory. He says that before, he thought he was good, but now he probably is !!
But - there is always the case of a great classical player who can't play jazz, a brilliant rock guitarist who can't play rhythm, etc. Just keep on getting better at whatever you do. I remember asking a guitarist, at a gig, when I was younger, how long he'd been playing." About 45 minutes," was his answer.
I'm sorry, I can't find the quote, it's pre-WWW.
But I think it was in an interview in "Guitar Player," that Keith Richards of The Rolling Stones once replied to some flattery by saying that he was only an intermediate guitar player. Because he was better than a lot of guitar players but a lot of guitar players were better than him.
So I'd go with intermediate. When I was learning, I always had the most fun when I was thrown in with players who were much better than me--they taught me how to turn my limitations into a distinctive style that added to the music we were all playing.
When answering this question I always answer with 'meh, I know a few chords'. This demonstrates modesty, which some people perceive musicians to be lacking and doesn't set anybodies expectations too high. If people are interested in you joining their band then no descriptions can really be a substitute for actually hearing you play.
Now, in terms of actually assessing your level of playing for yourself it should be against whatever yardstick you set. If you want to play like a certain musician, doesn't matter if its Steve Vai or Bob Dylan, examine how well you think you can do that. If you want to be a Grade VIII, then thats straight forward enough to check your progress against too. This falls under the learning cycle of pick a goal, work towards it, enjoy the satisfaction of reaching the goal, rinse and repeat. Personally I found this to be an effective way to assess my own progress.