With respect, Lord of the Sith was an AWFUL novel. I picked it up from the library figuring I'd give the new EU timeline a try. I won't pick up another.
All the new book does is give you a bunch of characters that you don't care about (on the rebel side), has a Palpatine who seemingly knows EVERYTHING, and
and is willing to waste the crew of a Star Destroyer to "test" Vader, and retcon whiny Anakin into whiny Vader - "GRRRRR! THe Jedi, Padme, and Obi-wan betrayed me! I'm mad!"
Sure, Vader did some cool stuff, and the throw-ins about how he's a legend with the storm trooper core were cool, but as a book to sell me on the new EU? Nope. Not even close.[/list]
Well, as always, it comes down to personal preference.
I liked LotS because it does set up Hera's motivations later (in Rebels) because of how that incident on Ryloth affected her father.
Palpy DOES know everything - it's been stated in canon and in the EU that he very much uses the Dark Side to 'see' the future, and manipulates accordingly. He's built as a character who is masterful at doing that, because how else does one man hold total control and sway over thousands of worlds, and billions of billions of billions of beings?
And the book does a better take on 'fixing' Vader to be the more badass villain we all knew he was, but Lucas was afraid to show.
I felt it was a really good look at Vader and Palpatine's dynamic, and showed very well how they worked together using fear, paranoia, and manipulation. That's a relationship that isn't easy to define, and the book did a good job with it.
But again - everyone has their particular taste. At least you tried, and you know what you like! Life's too short to read stuff you hate.