I bought Ozone 5 a few months ago after demoing it.  I've yet to explore all this tool can do ... it's VERY deep, versatile, and runs fine under X1 / X2.  You do need a powerful processor to run it on multiple tracks, though -- it can be quite CPU-intensive.
 
During the demo, the first thing I did was slap it on a full mix I'd been working on.  I hit a preset (something like "Rock / Pop Master") and was immediately struck at the transformation.  A "Wow" moment.  The mix just came alive to a degree that I've rarely experienced from a plugin.  Digging deeper, I found that most of the improvement came from the Multiband Compressor section -- the most versatile compressor I've come across. 
 
Add to that the extremely versatile (there's that word again) EQ, complete with a fun "matching" feature, the very usable saturation tool, the stereo imaging functions, and the advanced limiter, and you have something that can do just about anything.  Everything, that is, except pretend it's a piece of vintage gear -- that ain't Izotope's thing.  Although it's certainly possible to get a "vintage" sound out of it, you won't see simulated VU meters or shiny knobs.  What you will see are straightforward controls and useful metering with simple graphics. 
 
I also demoed Alloy and Nectar, but didn't find them quite so compelling -- many of their features overlap, and I found that Ozone did everything that I was looking for.  One of my favorite tools -- if you aren't familiar with it, download the demo and look over the manual.  You may be glad you did.
 
Note: no affiliation, just a happy customer.
 
Cheers,
Eddie
 

 I have O4 /O5 and Alloy. I am using a Q8400 Intel and my win7 x64 is only partly modded for DAW work. I chose to keep some things so I can run soundcloud on my DAW and perform a few other tasks on it.

 In my experience with this setup running 12 tracks loaded with plug-ins O4 was better than O5. O5 tended to choke my cpu occasionally depending on what I was running. Alloy is touted as a plug-in for track use, but in my experience it can also hit your cpu pretty good. As I  say these are my experiences with an aging quad core machine running a little bloat. Not unusable in all cases but sometimes the meter gets high. If I were to totally wash my machine I could expect better performance. If you load these plug-ins into a run of the mill computer it might not handle it.

 One other option is to mix a master and bounce it into another Sonar project for mastering with O5.

 Honestly out of my whole plug-in collection Ozone 5 deals the largest hit. Probably long overdue for a faster machine.

I have alloy2 with Sonar X2 in 64 bit enviroment. Love it. Alloy is light on CPU but sound great. Alloy is basically a mixer strip with EQ, compressor + gate ,trancient shaper, desser, exciter, limiter. All of this effect in one plugin plus hundreds of instrument and genra specific presets make this very attractive to me.  I tried the demo for 2 days and was hooked.

Jim Roseberry


If you're just starting out with 3rd party plugins, I'd also suggest looking at TRacks 3 Deluxe.
The "single" plugins load individually into any host DAW software.
You get some really nice souding dynamics/EQ/peak-limiter/etc.
The Opto compressor, Pultec EQ, and Peak-Limiter are particularly nice.

I have a copy of T-Racks Deluxe for sale (I have 2 copies) for $50 and you pay transfer...it IS Deluxe..not single...

I also have copies of SampleMoog and SampleTron for $30 each ( I have 2 of each now that I bought the
Total Studio 3 collection)
PM me and we'll discuss...

You should buy them both. iZotope rocks... "HARD!"

Check them out here.. www.reverbnation.com/rockinrobby