Records good quality audio through the built-in mic on the iPhone 4s. Metered display, EQ and limiting features make for a versatile free portable recorder app. 

TASCAM PCM Recorder is a free stereo recorder for iOS devices. It supports up to 12 hours of recording, using the built-in microphone or connected USB devices like the TASCAM iM2 stereo microphone. EQ, limiting, Soundcloud support and more make this a full-featured professional recorder.