Firefox played something well. As more and more browsing is happening from mobile devices they were not positioned well to go up against Safari nor Chrome. This had nothing to do with Firefox’s capabilities as that of a browser but rather both Safari and Chrome are based on Webkit while Firefox’s engine is different.
However, Firefox has a strong toe hold in the less expensive Smartphone market and now they just have to make it a foothold. Overall, their strategy looks great. Knowing they didn’t stand and chance competing with the Safari’s and Chromes of the world they tackled the less expensive market and with success.