TL;DR: I definitevely don't have anything against Bourbon, and we can actually use it with Compass (Bourbon for most CSS3 and Compass for utilities, spriting, compilation & other functions). But not using Compass is missing a big advantage Sass has over LESS.
- Doesn't work with libsass (yet — I read they plan on supporting libsass, probably later this year)
- needs Ruby (for now), and installs the
chunky_pnggem - Slow compilation (because parsing image sizes, assembling sprites… actually takes time)
- CSS3 Mixins of course
- when specifying a path to an image, Compass has a
image-url()helper, looking for the image and if it doesn't exist, raises an error. Extremely useful when cleaning the image directory — no risk of deleting an image that is used by a component. Same for fonts withfont-url(). - spriting: Compass makes it dead simple: http://compass-style.org/help/tutorials/spriting/ — awesome for performance and maintainability
- paths to images in production stylesheets: when compiling, Compass can distribute URLs to images with the
asset_hostconfiguration. For example,http://assets%d.ourcdn.comwhere %d can vary between 1 and 4. Handy to paralelize downloads — good for performance on desktop websites. asset_cache_buster: if the image has changed, appends a timestamp?1268738484to images. Can even be tweaked to beimage.1298698634.pnginstead ofimage.png?120798374.- Mobile dev:
inline-image(path/to/image.png)Embeds the contents of an image directly inside your stylesheet, eliminating the need for another HTTP request. Same with font files. - the
add_import_pathconfig option enables us to add Sass files from multiple sources, very handy for a modular architecture
image-height(path/to/image.png)andimage-width(path/to/image.png): If dimensions of an image change, the CSS is updated automatically with the new dimensions. Not mandatory right now but it's good when exploring theming, and a must-have on an internationalized platform (images can change depending on the language — Compass deals with it seamlessly)- CSS3 mixins are far better than in Bourbon, especially for advanced gradients, transforms and animations.
compass stats: returns a table of statistics about the CSS codebase (Sass size & compiled size, number of selectors, properties…). Very handy to track the evolution of a codebase and make sure it doesn't get out of control through a particular badly written commit. Example: https://gist.github.com/kaelig/749082823cb32ccdf36d
- Up-to-date documentation
- active development, and the developers in touch with the creators of Sass. Chris Eppstein (inventor of Compass) actually contributes on the Sass project as well.
- Heavily tested
- We can attach tests cases in the build system (in ruby though): http://compass-style.org/help/tutorials/testing/
- Help is easy to find, front-end developers usually know it: https://groups.google.com/forum/?fromgroups#!forum/compass-users
- I wrote a chapter about it in my book — I'm already proficient with it :)
Can’t forget the rich plugin ecosystem. Compass is way more than what you get out of the box.