If close combat Terminators are what you are looking for then the towel wearing Deathwing Knights are not the answer. While they may have Storm Shields they lack the punch to deal with power armour (or better) thanks to their close combat weapons. Yes once per game they can turn their maces into AP2 weapons but that just isn't enough in my books as I want that every single turn instead.
Rules wise though, if you had been playing Deathwing already you had been used to a uphill battle, and while the new rules gave you some tricks with the Deathwing Assault now letting you be twin linked, and I believe you can take larger units now?. You can't combat squad however, plus the current meta doesn't favor Terminators in general with Rate of Fire being all the rage at the moment. You can DS when you want and without Scatter with your fancy HQ, then split fire your fancy twin lnked guns, only to be torrented away next turn because of the meta.. This is a pricey unit to use as a suicide squad, so if you run them you need to put some thought into what you use them for. Deathwing are still playable with Allies, but IMO the list is now weaker if you take it without allies to help fill some gaps for things like anti air.
Deathwing is just there to make everyone who isn't a paladin feel a bit jealous. They are 4 points more expensive than vanilla termies, but as has been noted that brings some good rules with it and a bit better versatility with weapons. Split fire and vengeful strike mean a shooty squad of these has a lot going for it. Remember those Ravenwing Black Knights with scout, skilled rider and rad grenades. Oh yeah, they also have teleport homers, so who needs Belial. Well, unless you are in to troops I guess. You can scout the Black knights in to place behind a wall, deep strike the Deathwing in 6" away the other side of it, then move the knights out to soften things up a bit first. A lot of shootyness right where your opponent doesn't want it.
The command squad starts out the same cost as a standard Deathwing squad but gives access to banners, an apothecary and a champion with a rather nice Str+2 AP2 halberd. The halberd replaces
the initial storm bolter and powerfist. Can you then take a cyclone? Seems reasonable. The standard Deathwing squad lets you run up to 10 manz with up to two heavy weapons as well as throw in a few close combat options. It is going to be expensive of course, but it is going to hit hard too and it is nice to be able to build it exactly as you want it.
Lastly, the knights. If you can get over 2+/5++ armor that doesn't include a helmet the models look really good. In the game though they are a little odd. Fortress of Shields sounds nice but do you really want to be bunching up with all those nasty templates around. A lot will still wound on a 2+ even with this rule so it will be very situational. Hammer of Wrath is a bonus too, as is the WS5. The big downer is though, at AP4 their weapons aren't that great (unless you are playing against Chaos). But not great doesn't mean bad and if (when) I pick up a box of these the Black Knights is probably how I'll build them. Got a nice land raider for them already.