Does Windows Phone still worth something?

It's pretty much a dead platform, as they're no longer doing feature updates for Windows 10 Mobile. I used a Lumia 520 (WP 8.1) for four and a half years and finally ditched it 6 months ago. Kind of a shame really, since I loved the live tile UI and Windows Phone always ran extremely well even on low spec phones.

I can't imagine anyone would want to buy a second hand WP device for anything other than offline GPS mapping or as an MP3 player.

I once was a fanboy of Windows Phone but even I couldn't deny how badly Microsoft failed with the platform. They did too little, and it was simply too late.

Be smart and don't use a Windows Phone, period.

Sell that 650 asap and try to recoup the wasted money.

My phone and my S.O.'s cellphone only have single SIM's, so when travelling overseas, I loaded a tourist SIM (8 days, 5 GB LTE, unltd local calls/text, $20 CDN) on an old (2012/2013) Samsung ATIV S, then tethered our phones to its mobile hotspot as needed when doing email, GPS, and WhatsApp. Also gave our local relatives and friends an easy way to contact us via voice, text, or WhatsApp (still running on Windows Phone 8.1). Actually, any old LTE Android/iPhone would provide the same benefits, I just think it helps squeeze some utility out of the old device.