I absolutely love the tone/character/saturation of this thing. I don't just use it with guitar. Along with Sonimus Britson (Vintage Flat), T-Racks EQ 81 and and EQP-1A it is on every one of my tracks in a mix. The blend of these four ingredients in my spice rub makes everything sound delicious to me. Ignite Amps is incredibly generous to offer the TPA-1 for free.
This little plugin works exceptionally well; 100% professional sounding and free. I give it a 9 out of 10 simply because you have to cut the right channel routing yourself, though in Cubase this only takes a couple clicks on a stereo channel. Inserts > Routing Tab > snip/break right channel connection on appropriate slot. Note that any inserts on this channel you want to remain in stereo should come after ADT.
It gets a 9 out of 10 only because of the seriously ugly UI with controls that are not labeled.
This free little plugin blows my mind. I am basically using a single preset, "The Raf smooth", with minor tweaking per use. It takes any flat, boring, 2D sound and makes it 3D. It is great on a lead guitar. It takes the flat sounds of Padshop Pro and transforms them into worlds only found in dreams and movies. I can get lost in Padshop Pro with this plugin. It's almost too good because I don't want to make anything, but instead just zone out in the landscapes arising out of the pads. Haha. I love it.
In general, it can take a lot of experience and effort to make a pleasing sound on most synthesizers. With Razor, though it may be a little more trial and error to make a specific sound you have in mind, I find it difficult to create a sound I simply do not like. Pretty much everything that comes out of it sounds wonderful to me in some way. It just might not be what I was going for which I attribute to additive synthesis in general more so than Razor in particular.
Usability: 10 stars.
CPU: 2 stars (it hurts ... a lot)
Razor has quality settings, but it could use some even lower ones. Maybe use fewer partials?
Stability: 3 stars (due to Reaktor)
You can't review Razor without reviewing Reaktor as well. Reaktor is a nightmare to me. I keep hoping that some new version of it suddenly won't be, but alas, that has yet to be the case. Regardless of the instrument I am using it can crash out of the blue for no apparent reason. It will corrupt my Cubase project files so that I cannot open them. It is really rare a Reaktor instrument makes it to the final mix of one of my projects, and if so, there will only be that one instance.
Preset Management: 2 stars (Reaktor)
Native Instruments has a synth with my favorite preset management (Massive) and then with my least favorite by far (Reaktor). Bad preset management is also an impediment to sound designers releasing patch libraries for Razor. Sound designers I've requested Razor patches from have specifically mentioned this. Again, contrast this with Massive. [Sorry for the comparison KVR mods but I really want to drive this point home].
GUI: 9 stars.
My only gripe about the UI is that you cannot see the text value for a knob unless you change the value. Hovering over a knob should display it's current value.
If Razor was a standalone plugin I think it would be much more popular. An imaginary standalone version I would give 9.5 stars rather than 7. I would also pay considerably more for it.