Tascam DR-07 MKII

How long: a little over a week
I did many tests, recording in wav format, but you can also choose mp3 formats. Rendering an electro acoustic guitar is really respected that of an amp (Fender Supercontrol XD) also. Just be sure to set the recording level.

Have you tried other models, no, on the other hand I've researched, read reviews on other models (h1 zoom among others), downloaded the manual to know the features and capabilities.
The attached or downloadable instructions on the Tascam site is very comprehensive, understandable, it is best to read to fully exploit all the possibilities of the device.

What I like most: comprehensive, can position the microphones in XY configuration or AB, pretty easy to use, built-in tuner, very good quality recording,
well finished device can use rechargeable batteries (2 AA), comes with a 2GB micro SD compatible Mac. USB port to transfer files to or from the micro SD card.
The mic (located between the two microphones) input allows recording audio directly to a headphone output. Output on small hp for control (to avoid), or headphone output (preferred), or remove the microSD card and play it on computer with I Tunes, Audacity.

Report excellent quality / price, I would do this choice without hesitation.
Needing a device to save me trying to improve myself without ruining me, I am satisfied beyond my expectations.