What is your opinion of this product?
My only DAW experience is with Cakewalk/Sonar, so I cannot give a comparison to other platforms, but I will say that hands down X3 is Cakewalk's best product yet. So easy to use, and the ProChannel modules and post production tools are consistently rated as top of the class.
There are simply too many great things about X3 to include in a review here. My experience with X2 was a little less than stellar, as X2 seemed to be buggie and had issues with crashing. Whatever they did for X3, the problems no longer exist and those days of intensely aggravating crashes are behind me. Granted, X3 has had 4 upgrades to fix bugs, but it runs smoothly and I no longer find myself doing frequent "save" operations to make sure I don't lose material.
Compatibility is always a major concern for those investing time and money in a DAW, obviously. So far, I haven't found any 3rd-party plug-ins that Sonar cannot work with. I run a 64-bit platform, and all of my VSTs, 32-bit and 64-bit, work just fine.