I don't own this, but have a great deal of respect for Sony audio equipment.
Using the internal mics will record everything including many things your ears filter out, however, if you are away from excessive ambient noise this may not be a problem.
It appears to have excellent gain which is good, however, one reviewer has stated that this recorder is not suitable for hand holding since it picks up the slightest finger movement, and of course any wind noise etc which will be amplified.
For many people this may make it unsuitable for their intended use. If you are intending to use this on a stand then it will probably work excellently within the limitations of a wide field microphone. It is expensive, so think long and hard before you decide this is really what you want.
I would be very grateful if someone gave me one of these but I wouldn't be recording bird sound with them on their internal mics around here as there is too much other ambient sound. Great for music recording though!
If you want to use a shotgun mic 'built in' to a recorder, rather than hold it seperately, the Zoom H5 or H6 with the acccessory mono Shotgun microphone capsule (as oppposed to the similar looking stereo mid-side mic) may be worth considering. You will miss out on the exeptional range of choices for high gain, high quality recording with the Sony unit, but it may be closer to your needs.
Unfortunately I am guessing on your recording environment and you may find the Sony is what you need, it just wouldn't be where I live.
J