The key to the new guitar design is that all of the controls have been built into a central neck piece that is about 30" long and 3" wide. The strum bar, fret buttons, whammy bar, start, select, and d-pad (with 360 guide button) are all built into this base unit. Body pieces can then be snapped onto the neck to make your guitar look however you want. The body pieces come in separate top and bottom pieces, so you can mix and match different styles, which is pretty cool.
The only problem is the body designs available so far are kind of ugly and really, really make the guitars look like the plastic toys they ultimately are. Over the years, Guitar Hero and Rock Band guitars have actually gotten to be fairly nice looking. The Rock Band 2 Stratocaster looks really nice and not embarrassing at all, and the Guitar Hero: World Tour and GH5 guitars both look great and fairly realistic as well. But the Warriors of Rock guitar is over the top and cartoony. I suppose it fits the theme of the game it comes with, but I'm not really a fan of how it looks. I'd be happier with a normal looking Les Paul or Telecaster or Mustang body for it.
Looks aside, the most important part about a new plastic guitar is how it actually plays, and in this area the Warriors of Rock guitar handles pretty well. There are, however, some problems that come along with the new design. Similar to how the guitars have gotten better looking over the years, they have also generally gotten quieter and less annoying to play. The trademark, "click, click, click, clackity, clackity, click, click" has been quieter as the guitar designs have improved. For some reason, though, the Warriors of Rock guitar is the loudest, clicky-est guitar yet.
In actual gameplay, it performs just fine. The raised fret buttons feel great. The strum bar has a curved top (it is wider in the middle than on the ends) and feels good. I'd say performance wise, it is right on par with the World Tour or GH5 guitars.
Except, there are two major problems. The touch pad section on the neck has been removed. I love this feature on the other guitars, and it is sorely missed here. Warriors of Rock actually makes use of the touch pad feature in a lot of songs, so it is strange that it isn't even on the guitar that ships with the game. The other problem is the placement of the whammy bar. For me at least, the whammy bar on this guitar falls pretty much where my pinky is while I'm playing. I usually end up with the whammy bar mount between my pinky and ring finger or just hitting the mounting point with the bottom of my hand constantly. It is uncomfortable and distracting and an incredibly poor place to put the thing. I'm willing to put up with just about any of the other issues I have with the guitar, because it does generally play fine, but the whammy bar is just in an awful position.
One additional note I want to make is some tips on how to set up the guitar, because it isn't exactly obvious when you first pick it up. To insert batteries or change the body pieces, you have to take the top of the neck off. To do this, you have to press a silver button on top of the 15th fret, and while holding that button slide the top of the neck towards the strum bar. Now you have access to the batteries and the locking mechanism for the body.
To swap body pieces, move the locking mechanism down and pull the body pieces away from the neck piece starting at the tail of the guitar first. To put new body pieces on, put the highest tab of the piece into the top hole (towards the head stock) first, and then it will click into the middle and bottom mounts easily.
It is also important to make sure that you lock the head stock into position. There is a tab on the head stock to lock it, so make sure you do it. If you don't, the head stock won't necessarily fall off, but it leaves a gap between the neck and head stock right where you thumb falls that is very, very uncomfortable. Locking the head stock tightens up this gap so it won't drive you crazy.
All in all, the Guitar Hero: Warriors of Rock guitar is merely okay. I like it better than the GH2 Xplorer and would actually rate it above the GH3 Les Paul, but it isn't anywhere close to the World Tour or GH5 guitars. It plays fine for the most part, but it struggles in the looks department, is loud and clicky, and the placement of the whammy bar is absolutely terrible. The lack of the touch pad is also a definite downer and means the Warriors of Rock guitar is not my guitar of choice for something like GH: Metallica.
In the end, I would generally recommend the GH: World Tour or GH5 guitars over the WoR guitar. If you already have one of those, however, and want a slightly different feel or are interested in the custom body pieces aspect of it, the Warriors of Rock guitar is worth a look. It isn't an upgrade over the older guitars, not even close, but you can do a lot worse.