It's better than _The Merlin Conspiracy_ (two high-angst viewpoint charcters that, imho, weren't different enough from each other) or _Hexwood_ (I know there are people who love it, but I couldn't get into it), but not as wildly inventive as _Archer's Goon_ or as intense as _Fire and Hemlock_.
In any case, it's very vivid about the soul-killing pointlessness of being stuck as a servant in a noble house. The physical conditions aren't great, but they aren't awful--the emphasis is on what it's like to spend most of your time, and if you aren't lucky, your whole working life, repetitively smoothing the path of people who you're supposed to make sure don't notice you.
Jones gets points for emphasising that those upper class people aren't awful--they're just ordinary and oblivious.
There's a moment of genuine horror
when we find out that the whole elaborate probability distorting plot is the result of a man who wants to restore the manor house to its former glory, and we've been given at least a hint of the routine cost of that glory.
Unfortunately, part of the happy ending is that the servants from the shut-down noble house get similar jobs with the King. Imho, this is emphatically not good enough--it might be plausible, it might be better than the likely outcome, but a happy ending is supposed to make the reader happy, and I wasn't.
Odds and ends: This is a Crestomanci novel. For a change, the mother is neglectful and the father is vicious. The only other "being a servant sucks" fantasy novel I can think of is _The Ill-Made Mute_ by Cecilia Dart-Thornton.