I've never seen it, is it any good?
I think the first 2 seasons are good.
The rest ( so far) not so good.
The reason I think this is because of the casting.
The actors playing the Queen, Prince Philip and Princess Margaret in season 1 and 2 disappear into their characters and work well.
So those two series are enjoyable.
When they were replaced with older actors, I feel the characters they played were lost and all you saw was the actors.
Olivia Coleman as the Queen in particular. She wasn't right for the part and ruined it for me because she just did not convince as the Queen.
I actually think using ageing make up etc on some of the original actors would have been preferable to the cast change.
Of course that would only work with the Queen, Philip and Margaret.
The guy playing Charles after series 2 did a great job.
Also, the writer hasn't portrayed everything accurately.
And, of course, the scenes where Royals are alone with each other cannot be anything other than the writer's invention because no one else was in the room to witness what actually happened.
I think the cast of the upcoming season might be better.
I'd say give it a go.
But always remember, it isn't accurate.