Spend a little bit extra and get something with more inputs and at least 60dB of microphone preamp gain. For example, I have a Tascam US-2000, which isn't much more expensive, and with that you can record an entire band at once (14 channels total, with 8 mic preamps). I use one for live recording one of my bands, and it works great. Love the front-panel metering, good 64-bit drivers, etc. The only weakness I've heard about that unit is the XLR jacks on the rear have a tendency to grab cables and not let go. So I use some short XLR extensions and leave those plugged in permanently.
I have seen them for less than $300 brand new... Amazing really.
Tascam also makes a cheaper one called the US-1800, but there are a few things that scare me away from that model. There is no internal power supply; the mic preamps are weaker (+58dB); and lots of reports of units malfunctioning after a few days. I'd avoid that one.
If you don't want or won't ever use the extra inputs, the Zoom R8 is really a cool USB interface for the money. With that, you can record standalone to a SD card, OR use it as a USB interface and control surface
with your favorite recording software. http://www.zoom.co.jp/products/r8/