Firstly, I'm a little surprised by the number of 10/10 and 1/10 reviews!
One of the main issues people seem to have is the 'historical' tag. It's about as historical as 'Blackadder' - that is to say, it's not. Thankfully, this is made abundantly clear in the first few minutes of narration. It's essentially an alternate universe vaguely grounded by one point in time and centred on a very fictional version of Jane Grey.
There's a lot going on and it certainly demands a significant degree of suspension of belief. However, it does set up the 'rules' of its setting, characters, and style of storytelling clearly within the first episode - and it stays true to them. If you can't enjoy the first episode, this one's not for you! If you can happily suspend your disbelief and lean into this frothy romantasy - you're in for some fun bingeworthy viewing!
Without spoilers, My Lady Jane is about an alternate-universe Jane Grey, who is forced to marry the apparently rakeish and brooding Guildford Dudley. Brooding sexual tension ensues as the two navigate Jane's ascension to Queen, court intrigue, power struggles and the persecution of the Ethians (the magical human-animal shapeshifting equivalent of Protestants).
Is the plot messy? A little. Is the *modern* sexual content, music, and swearing overdone? Absolutely. This series could have been GREAT, like the lovechild of Blackadder and Princess Bride (with a little LadyHawke thrown in for good measure), but it didn't quite get there. The chemistry between the leads counts for a lot - Edward Bluemel really pulls off the swoony moments to perfection! There's some very entertaining support characters which grow on you through the series, particularly Rob Brydon's Lord Dudley and his son. Yet I feel it's held back by not knowing its target audience. This story could have been a perfect frothy fantasy sattire for a much wider audience without the gratuitous sexual content and swearing. The older members and teenagers of my family could have loved the story and watched it again and again. It could have been the ultimate family guilty-pleasure weekend viewing. But instead, it's only suitable for some adults yet isn't a mature enough story to truly achieve greatness in that context. A missed opportunity! But still a very fun and enjoyable series.