At first glance, Crunchbang seems to be targeted at people who want a lightweight distribution and don't mind occasionally using the terminal or editing text files. While the Crunchbang website's download page still contains the following disclaimer--
CrunchBang Linux is not recommended for anyone needing a stable system or anyone who is not comfortable running into occasional, even frequent breakage. CrunchBang Linux could possibly make your computer go CRUNCH! BANG! Therefore CrunchBang Linux comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law.
--this warning seems to be a leftover from previous, Ubuntu-based versions. With version 10 (codenamed Statler after the Muppet Show character), Crunchbang has switched to Debian stable as its default code base. This move makes Crunchbang a plausible option for users who do value stability.
However, all I can do is speculate about who might find Crunchbang useful, since the distro's developer has insisted in a blog post that "CrunchBang does not have a target audience."
Crunchbang 10 uses a fairly simple installer that goes through all the standard setup questions (time zone, keyboard layout, etc.) quickly. The only possible snag is that, unlike Ubuntu's installer, this one doesn't automatically detect other OS's on the machine. This omission may cause problems for users who aren't familiar with the nuances of GParted. Another minor issue is the inability to install from the LiveCD session. You have to reboot and select the install option from the LiveCD's menu to start the installation. This last point is only a slight inconvenience, though.
Welcome Script. The first time you boot Crunchbang up after installation, the terminal opens and offers you the chance to upgrade the package list and install several optional packages, such as CUPS, Java support, and Open Office. This is a convenient tool for users who always make these changes right after installing a new distro.
Chromium Out of the Box. Crunchbang comes with Chromium pre-installed. This is a huge convenience for people like me, who use Chromium as their default browser and always have to download it for every new distro.
Speed. Crunchbang comes in two versions: Openbox and Xfce (more on that later). Both are incredibly fast. In fact, I was surprised at how much faster than Xubuntu Crunchbang Xfce was.
Choice of Interfaces. Many lightweight distros come with only one GUI. Crunchbang allows you to download either an Openbox or Xfce version. Furthermore, the welcome script allows you to install support for multiple sessions, so you can choose to have the other interface available when you log in. Unlike some other distros, when you run the non-default interface, you get the full experience of that environment. You aren't left staring at a blank screen when you open up an OpenBox session in Crunchbang Xfce. This is a boon for users who want to experiment with an unfamiliar interface.
Unusual Default Layout. Crunchbang's default desktop configuration doesn't include a menu button, even in the Xfce version. I found this only a minor annoyance (and easily fixed in Xfce). However, someone less experienced with Xfce might not know how to fix it. Such a person also might not think to right-click on the desktop, which brings up the full Xfce menu.
Software Updates. Since Crunchbang is based on Debian stable, new versions of software will be slow to come. Right now, this problem isn't too noticeable, since Crunchbang 10 just released with Chromium 9 and fairly recent versions of other programs. However, many of these programs won't be updated to new versions until the next Debian stable is released in 1.5 to 2 years. This problem can be solved by switching to either the testing or unstable Debian channel.
Hardware Compatibility. Like any non-Ubuntu-based distro, Crunchbang 10 may have compatibility problems with a lot of hardware out of the box. For example, I had to give up on using Crunchbang with my laptop because I couldn't make it work with the wireless chip. To be fair, this particular chip seems to have massive problems with a lot of Linux distros, and Crunchbang works with every other piece of hardware on both my desktop and laptop. I've also heard that Crunchbang (and Debian Squeeze) support a lot of otherwise troublesome hardware, like Broadcom wireless chips. Really, this is just a general warning for anyone who has been spoiled by Ubuntu's incredibly broad hardware support and expects every Linux distro to plug and play with every bit of hardware.
OpenBox vs. Xfce
As I've mentioned, Crunchbang comes with either Openbox or Xfce as the default GUI. Each of these environments has its own advantages and disadvantages. Here are screenshots of both desktops' default configurations:
Both environments come with a system information panel in the upper right corner (courtesy of lightweight system monitor Conky) and a panel at the bottom with two workspaces. The Xfce version also features a second, auto-hiding panel that functions as a dock-like task launcher. I found this feature convenient and started adding it to other Xfce-based OS's I ran. Other people consider it an annoyance. To each his or her own.
Neither version has a menu button when first installed. This problem is easily fixed in the Configure Panel dialog in Xfce. There seems to be no easy way to get a menu button in Openbox, but the lack of one doesn't cause as many problems in Openbox either. Right-clicking anywhere on the desktop or on the panel brings up the full menu, so you can always access the menu, even with a maximized window on screen. This is not true in Xfce.
The major difference between the two environments is how to customize the desktop. In Xfce, there are GUI dialog boxes for most common customization tasks. In Openbox, on the other hand, most configuration is done through text files. Fortunately, Crunchbang lists the major configuration files in the menu, saving you from having to know the exact name of each file to open it in gedit. Unfortunately, the text files are often long and can be confusing to people who can't figure out the format or what the terms mean. Whether you are comfortable working with these text files should be the most important factor when choosing Openbox or Xfce as the default session.
Personally, I've found Crunchbang to be a good tool for exploring OpenBox. I downloaded the Xfce version because I'm more familiar with that environment, but I enabled multi-session support so I could play around with OpenBox when I felt like it.
I wouldn't recommend Crunchbang to a novice. It's most fit for users who have some experience with either Linux or programming. However, it's a great distro for experienced users who want a light and fast OS, who want to learn more about the inner workings of Linux, or who want to experiment with unusual user interfaces.