Ok, so ... just got my copy of the Necron Codex. I haven't finished my analysis of it and I likewise haven't decided if I'm going to shelve my Necrons because of it, however ....
The first thing I'm noticing is that Destroyers are the road to failure. I've never actually fielded Destroyers, because they take up a fast attack slot, and given how badly Necrons have always blown in close combat, I've found unless I'm fielding at least one unit of scarabs (two are preferred), I can bank on losing my entire army in sweeping advances. In the old rules, at least "we'll be back" mitigated this to some degree, but the new rules make it worse, since all downed Necrons self-destruct if their unit falls back. I used to field heavy destroyers (usually one unit as fire support with two monoliths), back when heavy destroyers were classed as heavy support. Now, they are simply a Destroyer upgrade. So, looks like all my destroyers get shelved at the very least.
The other thing I noticed, and was wondering if others have noted (I hadn't seen this posted yet, so apologies if I just missed it), is the implications of Imotekh's Staff of the Destroyer on close combat. The staff is basically a template weapon - pick a direction, fire and it hits whatever is under it. Unlike a normal template weapon, however, you don't have to actually fire it at anything. This means he could willfully fire it in the direction of, say, a squad of marines surrounded by scarabs. This stands a good chance of annihilating the marines, leaving most of the scarabs able to lock something else up next turn. Of course, this is a one-shot deal, but still ....