He told me to take it as well, any level, just to see how well I can do.
Well, I would take a level that makes sense for you. I guess it depends on how you study. If it helps you to have a test coming up to sit down and study, then do the test, if you can motivate yourself to study even without a looming test date, then not taking it is fine.
I searched around the internet and a lot of people say that anything beside an N1 certificate is useless. I am wondering if I would get any certificate or some kind of proof that I passed a level besides N1. Would it look good on my resume?
I think this greatly depends on the type of purpose you want to use it for, and if you are European/American or Asian. I would say that for Europeans/Americans (or as the Japanese would say 白人) even N4 might have some value, while most Taiwanese/Chinese immediately opt for at least N3, even if they often don't know yet practically any Japanese. But as the test is about reading/grammar only but not about writing or speaking, if you know kanjis it is easier to approve.
Obviously only N1 certifies that you are very good at Japanese and it is also the only certificate that is recognized in the process for asking for a work visa (e.g. Highly skilled professional). Also I think if you want to study in a university in Japan they will want N1.
However if you plan to just work in a Japanese company, already N2 is okay. Depending on the company. If you want to work in a company with connections to Japan or where some English is spoken even an N3 will give you an advantage. Essentially Japanese companies love certificates. N4, I would agree is not terribly helpful, unless you are one of these persons (like me) who studies better with a looming deadline.
And yes, you do get a certificate for passing any level, including N5.
I don't mind taking the test just to see how it's like. But the test is right before my final exam, and I am worried that I might not have enough time to study for it. I have 5 classes and a part time job. If I fail, it would be a waste of money and time, so I am still considering.
Well, this sounds stressful and if there is no good reason to add yet an other stress factor to your life you might want to head for the July JLPT (if that is offered where you live).
It's not too late to register now, though, is it? The website doesn't say anything about deadline for registration.
Registration for Dec exam will start in Sep.
For those who have already taken it, on a scale of 1 to 10, how difficult do you think it was?
This obviously depends on how well you know Japanese and which level you took. However I found the time pressure is your enemy. Essentially you need to read the question and answer options and IMMEDIATELY need to know the right answer. If you start thinking about it, you will loose too much time and will not be able to finish the test. So if you sign up for the test, or even now before signing up for the test, do one of the mock exams that are available on the internet and put yourself in the test situation. I.e. no book, dictionary... and only the allotted time. This should give you a fairly good idea how difficult the test on a 1 to 10 scale is for you. And at the end, let's be honest, the only thing that matter is how difficult the test is for you, what others say will not have any impact on how you will experience the test.
Enjoy studying Japanese!