Looks like the book, for the way I like to play armies, has the same problem the last one did*;
1) they are minimum 25% slower than the next slowest army and in many cases 40% or, against cavalry, even more, meaning the opponent determines point of contact and who is involved in the festivities the slayers are worse than useless, they are free points for the opponent as anything slow enough to get caught by them can shoot them down before they get to it 2) 1 attack per model = fail unless you can choose the combats
3) Slayers, with their max 6" move when not charging, are going to get shot down or flat out avoided by anything they could threaten.
Slow army, pedestrian number of close combat attacks, I will go flip through a book and hope it changes my mind, but the slayer thing alone is so disappointing I went from planning to pick up a book yesterday and play them next Saturday against one of my brother's Dark Elves to thinking the Dwarves are staying on the shelf unless/until another book is shelved.
An army that maneuvers slowly, is too expensive per model to be able to take units large enough to control space, and cannot put out enough attacks in a short enough time to swing a combat just isn't all that exciting. I really hope people use the book better than i would and prove me wrong because it has been a long wait for this one.
* All comments should be construed as including the idea "for my play style", other play styles will get varying mileage. I tend to like compact, maneuverable armies that can withstand and deal out a decent amount of punishment. I also play Orcs and Beastmen but have been trying to put together a High Elf list for about 6 months now and have yet to find one that fits my style. No need adding another one to the list at the exorbitant price the books are now...please, convince me I am wrong, I am trying to find a reason to buy the book and have not been able to talk myself into it yet.