I have had 4.0 for 220 days and a happy customer, until I upgraded to 5.0 Life. The readings are way off, often it says Whoop are off body, but I had it on for days and all is good, battery, firmware etc. Also very different readings compared to the stable 4.0. In short, the 5.0 is not an upgrade, its a downgrade and I will ask to get my money back, and use my 4.0 instead. Also the quality of 5.0 feels a bit “cheap” and not solid and nice as my 4.0. It seems like the product development team was to busy getting 5.0 out there, instead of testing it and refining it, before pushing it to market. A shame and a bad customer experience 
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I’m feeling the same tbh. More because of the way it now calculates readings and tells me time outdoors (for example) is having a negative impact.
New strap too, so the purchase I made a few months ago is wasted.
14 day battery life is nice, but the 4 wasn’t terrible. Feels like they’ve lost their way as I’m no longer trusting the information it provides. Worth also mentioning it’s inability to detect things like walks and HR acuracy.
I could go on but 5.0 is not progress.