Okay, so I've been using these itayak behind-the-head headphones for about a month now, and here's my totally unfiltered take.
First off - the comfort? 10/10. As someone who hates in-ear buds (they always fall out!), these are a dream. The neckband design is lightweight and doesn't squeeze my head like some over-ear models do. I can wear them all day at work without that 'headphone headache'.
The sound quality surprised me! For the price, the bass is decent and voices come through crystal clear. Not audiophile-level amazing, but way better than I expected from wireless headphones in this range.
Battery life is insane - I charge them maybe twice a week with daily use. The Bluetooth connection stays solid even when my phone's in another room (though one reviewer mentioned issues - maybe they got a lemon?).
Only downsides: The controls take some getting used to, and yeah, that voice notification when turning on is LOUD (why do companies do this?!). But overall? For $30-40? Absolute steal if you want comfy, no-fuss wireless headphones.