For many projects, the BeagleBone Black may be a better choice. It's available for $45, but has nearly twice the CPU performance, 2 GB flash built-in, and perhaps most important for some projects, has lots more I/O capabilities. Sure at $10 more, it seems almost 30% more expensive than an RPi, but in most cases that won't matter especially after adding an SD card, and a cable to the Rasbberry Pi.
There are lots of comparisons already written. Some also try to compare with the Arduino which is really a different beast but it's somewhat understandable given the prices and that it's all "DIY".
Here's a useful comparison:
- How to choose the right platform: Raspberry Pi or BeagleBone Black, by Michael Leonard, Posted in Make
Without summarizing/rewriting the whole comparison, here are the bits that I think are most useful.
Choose the Raspberry Pi (RPi) if you want to:
- Build an HDTV connected media player or DIY Linux computer with a full GUI. The RPi does 1080p 1920x1080 with a regular full size HDMI connector.
- Learn or give a gift to someone who wants to learn as the RPi has a much larger community and better tutorial coverage.
- Note the BeagleBone Black, is actually much easier to get started with, and most of the tutorials for RPi should be able to be translated without too much effort, but that might be too daunting for some just learning with no support network.
- Build projects that need more compute power or lots more I/O connectivity
- HDTV connectivity at 1080p isn't important to you.
- Get started more quickly, the OS is already installed.
- have both USB Host and Client mode. (The BeagleBone Bone can act like a computer, USB host mode, or it can act like a device that needs a computer to control it.)