Measures approx 12 cm by 6 cm by 2 cm so a reasonable pocket size.
Records in MP3 or WAV formats, variety of different sample rates available.
GREAT quality of sound recording in the places where I have used it.
Up to about 3.5 hours recording time on a 2GB SD card, depending on format used. And you can get bigger SD cards.
Very easy to use - turn it on, press the record button twice and you're away!
Mine has no battery cover and this makes no difference at all - the batteries stay in place 100% by themselves and do not shake out in transit or use.
The only thing I don't like is that the 'hold' button is not easily accessible when the unit is in your pocket or bag, and if you don't use this function then it's easy to accidentally press the stop button (especially if you are recording something with the item in your pocket and just the microphone part protruding).