I think "uber" high detailed maps (like It Lives or The Thing) are good examples of what is possible to achieve in detail level, even if a new map with the double of detail than It Lives were released (very complex spritework, micro sector design, high detailed shadows, and whatever you can imagine) we could know that it was possible a-priori, that wouldn't be really great news, if you think about it, the only merit would come from that crazy mapper doing the amount of work necessary to achieve it. Mapping in that fashion is a linear path, imho, you know how it will end.
On the other hand, take for example It Lives and its great new effects, those for sure, were really new things to most of us, and made us wonder: how the heck did he managed to do this effect! Or Happy Hang over, both are high detailed but with great and innovative gameplay. (Well, not really new gameplay mechanics - like blowing doors instead of using keycards

About classic styled maps I'm so fond of they, because feel like if new original maps were released for the first time after all these years, which adds a nostalgia factor. That's why I liked so much Legal Joint. Obviously I'm not saying that original DN3D maps are good to my eyes just for nostalgia...
There are as well that other type of maps, that everybody seems to forget on this discussion, which instead of going for a "realistic" style they go for a surreal style, most of William G maps enters in this category imo. They could fit better on classic style at some point, but with conceptual grandness detail. Look at WGR2 maps they aren't so detailed, there are even squarey in places, that is what makes William G such a great mapper, he already managed to apply the "Less is more" rule to mapping.
As a conclusion, as someone already pointed before, I consider that diversity is the key of everything.
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So according to the statistic so far, if there was a map with great gameplay but it has two versions: a high detailed one and a classic version (whatever that means, I didn't invented the term) people would prefer the high detailed version.
There's a generalized opinion about classic maps being released as frequently as always, versus more detailed maps.
It seems that most people here think both kind of maps are getting the same attention. Let's see how the stats evolve on the next days.