Tempting, but the camera needs to be better.
Thanks to some very speedy bandwagon jumping last year, I received my Gemini 2018-03-01. Given my jump was on 2017-02-27, it's been quite tough to suppress the schadenfreude when reading rants from people suffering the agony of a mere few months wait...
When plans for the camera add-on were announced, I didn't properly consider how much I would notice the absence of a camera.
The built-in "selfie" 5MP camera does a very good impression of a 2MP camera, thanks to a lens diameter about 0.5mm and a sensor worthy of a spy's stealthy camera.
My previous phone, a bargain Wileyfox Swift 2X, had a 16MP Samsung sensor which produced reasonably good photos. Prior to that I had a ZTE Blade S6 with a 13MP Sony Exmor IMX214 sensor, which replaced a Moto X 2014 (sadly drowned after only 9 months) having a 13MP Sony IMX135 sensor which received middling reviews for its photo quality.
The add-on camera's 5MP camera falls well short of those fitted to other "enthusiast" Android phones.
Even the Raspberry Pi Camera Module v2, released April 2016, has an 8MP Sony IMX219 sensor and only costs £26.
£40 is too much for a 5MP camera module.
Biting the hand that feeds IT
