"And maybe now you guys understand..." is a little patronising. It's not like we haven't thought of some of these issues over the past 9 years since UnrealSP.Org started...
I think Shivaxi's choice of wording was unfortunate. The way I understand it, it was meant to emphasise that opinions about certain aspects can vary (which you acknowlegde), and (this is my extrapolation of Shivaxi's reaction) that he sees some justification in my remarks, just as I see justification in other remarks made by other players with other maps.
The major problem with single reviews is that it is almost impossible to compare gameplay of the current map under review, with the gameplay of a map which was played a year or longer ago.
The example which comes to mind is ONP whch I have finished a couple of days ago - there are weak gameplay situations in there, but ONP is 30+ maps (38 IIRC) and looking at it as a complete pack - I think it's still good, even though it's aged). Now gameplay errors in a short pack or in a single map will leave a more lasting impression. Other aspects to take in mind are the preferences of players - I like lots of puzzles, and cautious progress - UB probably likes rougher fights, I liked the 3 Skaarj Hill because it looks so daunting, but leave your allies out of sight of the Skaarj and stay out of sight yourself, and your allies stand a better chance of taking on a single Skaarj and you are left with only one Skaarj to deal with. Some may say this is gameplay design fault - I say this opens up new tactical possibilities. The question of which is better is pointless - what is important is whether the majority of players find an enjoyable way to hadle the situation.
With this in mind I think Gameplay Awe and Conceptual Grandness are probably the aspects most prone to great differences in individual opinion.
Looking back at ONP, last week the Conceptual Grandness didn't hit me (I still recognised it) at it did when I first played it. By now, in 2010, I've played almost every pack and map there is and I've seen every new Conceptual Grandness thing so it's natural that older maps will suffer a lower score because of age itself.
Concerning Gameplay Balance I can (in my own way) judge ONP, and Xenome, and Vigil - why? because I've played on all (or almost) all difficulty levels. A single reviewer probably doesn't want (or have the time) to play all difficulty settings so I guess the review probably describes Medium difficulty, which may just not have been the adequate difficulty setting for the reviewer. I have played those maps on difficulty settings way too easy for me, but also too difficult for me so I know if there is a (and which) setting really gave me maximum pleasure.
Anyway, Shivaxi's review wasn't being scrutinised by me, all I did was state some areas where I differ in opinion (as I do with other reviews) and it seemed to me that Shivaxi, without turning his back on his own review, can see why his review of some aspects is bound to differ from other's reviews.
I am not really in favour of one review by a group of testers, but I would applaud many individual reviews on the gameplay aspects.