First month of new map rotation system just passed, some commend it, others aren't too happy about it.
However, it surely shows that the activity has dropped regardless of your opinion about it.

The lack of activity was most prominent on duel servers, where one of the most played maps was removed from public servers and only available to subscribers.
September's rotation again lacks competitive duel maps, which are crucial for the activity of standard servers. Clan Arena players will suffer the most with the removal of Campgrounds. We will be able to see and play some RA3 maps such as Theatre of Pain and Evolution.

21 arenas will be selected and update each first monday in month.
An arena has to be at least 3 months old to be eligible for the standard cycle.

Official news

The standard map pool now includes the following maps:
Arena Gate
Blood Run
Cold War
Courtyard
Demon Keep
Dies Irae
Evolution
Forgotten
Gothic Rage
Grim Dungeons
Hell's Gate Redux
Overlord
Rebound
Siberia
Skyward
Sorrow
Space Camp
Theatre of Pain
Toxicity
Trinity
Vortex Portal

and it's active from September 3 to October 1.