The tool is fast, but it is the input that makes it deadly. Brainflayer allows the user to supply wordlists (dictionaries).
: Major services like Brainwallet.org shut down permanently after researchers proved that any human-chosen phrase is effectively guessable by modern hardware. brainflayer
: Most people use song lyrics, book quotes, or common patterns that are easily included in cracker dictionaries. The tool is fast, but it is the input that makes it deadly