To see Armin van Buuren himself review some of the standout tracks from this era:
The classic 138 BPM+ sound was being challenged by a slower, groovier, more progressive tempo (128-132 BPM). This was the era of "big room trance." Purists argued it was a sellout; progressives argued it was evolution. Armin van Buuren, ever the diplomat, did not pick a side. Instead, he curated a double-disc album that bridged the gap. a state of trance 2012