Cross-posting from an AskTechnology thread:

Thinking about purchasing one. I do not need to measure event-related potentials (which are of much smaller magnitude), just want to see the standard indices of rhythmic activity (especially as they relate to the alert/bored/sleepy axes). Many reviews on the web focus on them being crappy for ERP, which doesn't bother me because that's not what I'll be looking at. I'm curious if anyone here is willing to chat about their experience--easy to setup? easy to get quantification of intensity within the standard spectral bands? how long does it take to get a stable read? too sensitive to facial muscles? other concerns?