How far can it really see at night?

The maker rates it at about 150 m in complete darkness with the IR illuminator on. Real range depends on how dark the scene is and how much IR reflectivity the target has.

Does it work in daylight?

Yes. It has a daytime viewing mode, so you can use it as a zoomed monocular in normal light as well as at night.

Can I record what I see?

Yes, it has built-in recording for video and stills, so you can save what you spot without a separate camera.

It uses a built-in 3000 mAh rechargeable battery. There is no external battery pack to carry.

It comes with a helmet mount, a head band and a neck lanyard, so you can wear it hands-free or carry it around your neck.

Is it as good as a Gen-3 night vision tube?

No. It is a digital unit, so it shows more grain and has shorter usable range than Gen-2 or Gen-3 tube devices, but it costs far less and adds recording and zoom.