Bootstrap 3 has been available since August, and there have been some pretty major changes to Bootstrap since version 2.3.2 (see the Bootstrap information for a list of changes). We decided to wait until Bootstrap v3.0.3 to update our concrete5 theme, Coffee Bean, as there were a few little niggles that Bootstrap had to fix. One important thing to note is that Bootstrap 3 is not backwards compatible, so if you are upgrading from Coffee Bean theme v1.1 to v1.3, you will need to be aware that there have been a lot of changes. Please see information on migration from Bootstrap v2 to Bootstrap v3.
What are the major changes to Bootstrap that have affected the Coffee Bean theme? Well, a big one is that images in Bootstrap are no longer responsive by default. If you want an image to be responsive, you need to apply the class "img-responsive". We have added a responsive image block to the theme so that you can easily add responsive images without needing to add the "img-responsive" class yourself.
In addition, there are some slight changes in appearance with the new Bootstrap. For example, the dropdown menu appears slightly differently in the new version. For the most part, the appearance should be the same or very similar.
The new Bootstrap has some very useful new features. We are especially excited about their new grid classes which enable developers to specify the grid class for different browser sizes, see their grid options . Say for example, you wanted to have 3 columns showing on a full width screen, but only two columns showing on a tablet, you can now add classes for this. In Bootstrap v2, the columns would just stack automatically and the developer did not have that fine control over the number of columns in different browser widths.
We also like the glyphicons that come with Bootstrap 3, see the Bootstrap documentation for more information. These glyphicons have lots of options, such as using them in buttons, button groups for a toolbar, navigation, or in forms. There are 200 glyphicons to choose from, so you should be able to find something that will work for your site.
Bootstrap 3 has many more exciting features...check out the Bootstrap 3 website for more information and examples.