Some notes on Helvetica and why it isn't really suited for text (can work as a headline or a warning sign, but not in OSX or IOS).
Why is Helvetica so popular? This question is not so difficult to answer. First, Helvetica was aggressively marketed in the 1960s. Second, Helvetica became almost the only typeface to be used by the Swiss typographic style of that era, which continues to be very influential. The third reason is that Helvetica is neutral and colourless; it is not dangerous. This makes it easier for graphic designers to use as a display face. A typeface that already has a lot of character determines the character of a poster or a book jacket. With neutral Helvetica, the character must come from the typographic designer. This makes Helvetica beloved by many. One can make a good poster with a bad typeface, but one will not automatically make a good poster with a good typeface.
In the past 50 years there have been many beautiful graphic designs using Helvetica, but this has more to do with the quality of the designers using it than that with the quality of Helvetica as a typeface. Frutiger explained its popularity with the words: 'Helvetica is the jeans, and Univers the dinner jacket. Helvetica is here to stay.'
As a text typeface Helvetica is an awkward creature. It is only because it is available on all computers that it is used by so many people around the world. You cannot blame them – they have no typographic education. They just have to set some text in some typeface. Unfortunately, Helvetica is about the worst choice one can make for text. Paul Rand, the American graphic designer, advised his students to use Helvetica only as a display face, and never in text, 'because Helvetica looks like ******* in text'.
http://www.eyemagazine.com/feature/article/inclined-to-be-dull