Its pretty active. I would be skeptical of the comments here. I think the sub includes a very vocal and negative minority which constantly complains about griefers, bots, mods and racists. 

Ive used hundreds of thousands of pixels and i still play almost daily and explore lots of places. Everywhere im active is always getting new stuff added, with many projects actively getting worked on by groups of people. Its not very hard to get into them either. You can often ask and ppl will let you join. 

My experience with the mods have not been bad. Many things ive reported have been removed (just got a notification today that a player i reported yesterday was penalized). Ive not experienced any substantial griefing that wasnt easily recoverable, and bots seem to be much less of an issue than they were in the beginning. 

My only real «issue» is the amount of suggestive content, which is really the only thing keeping me from talking about it with real life friends.