Turning something as complex as the quality of a journal into a single number can never the completely right. If the journal is in my field, I would look if there are milestone papers in the journal that moved the field forward, and at the quality of the articles in recent issues. It's subjective, but if you use the number only you rely on other people's judgment, who probably have their own agenda. Just running after the crowd is not how researchers should think in my opinion.

If the journal is outside of your field, the IF might be one of the few clues to judge the quality, but it should only give the ratings 'journal seems irrelevant,' 'solid,' and 'may be high-quality' ... Some journals use suspicious practices like telling the authors to cite more previous articles in the journal before being accepted just to increase the IF, so it's not safe to rely on IF alone.

Turning something as complex as the quality of a journal into a single number can never the completely right. If the journal is in my field, I would look if there are milestone papers in the journal that moved the field forward, and at the quality of the articles in recent issues. It's subjective, but if you use the number only you rely on other people's judgment, who probably have their own agenda. Just running after the crowd is not how researchers should think in my opinion.

If the journal is outside of your field, the IF might be one of the few clues to judge the quality, but it should only give the ratings 'journal seems irrelevant,' 'solid,' and 'may be high-quality' ... Some journals use suspicious practices like telling the authors to cite more previous articles in the journal before being accepted just to increase the IF, so it's not safe to rely on IF alone.

The impact factor has been criticized a lot (see e.g. http://en.wikipedia.org/wiki/Impact_factor ) and a high impact factor does not automatically guarantee that a specific journal is very good (maybe it is high because of self-citations, maybe because of publishing lots of review or methodology articles that usually get cited more...). Also, all journals without the impact factor are not automatically bad. Still, usually people tend to know which journals are good in their field (e.g. at conferences, some people analyze articles in top journals of their field) and some institutions have also made lists of top journals or almost top journals (mostly they include journals with impact factors but e.g. in UK some 1-star journals do not have them)

Accepting quality papers is very important : http://ijaridea.com/Web-of-Knowledge