Sorry for the whining post in advance
- the name is OperaHouse, and the only Opera-ish thing in it is that grey unnamed building in the middle
- many map flaws, such as invisible blocks, non-aligned textures etc
- bad global design - so much space, so many places to use - and so little space is actually used. You can never tell if that ruined house contains a node, a superweapon, a path to core, a clown from far space or just nothing. You can let 32 players there and they can wander around and never see each other
- bad local design - you can never tell where you are without a minimap... everything is alike in the bad meaning of this word
There are couple of good sides, though
- the "destroyed city" setting with buildings and all - it's nice to see that map has own style
- semi-open world (not Bitchslap corridors and not Kingdom fields)
- pretty good nodes layout (there was no clash on 1-2 nodes with other left idle)
What I can recommend about it:
- create artificial walls around the map (ruined buildings, debris... whaterver, just not the blocking volumes in thin air! at least the map borders could be different from all the other map elements)
- A hard one, but still: change internal buildings architecture. The good example is Call of Duty 2 Russia multiplayer maps - even with many doors, windows, holes in the walls; even with many corridors, rooms and multiple floors - there are almost always only so many entry points in any given location, or the location is of "arena" type. What is the use of 20 randomly placed ruined buildings on 100x100 meters square if they do not offer anything in tactical sense but, well, using them as obstacles?
- Change buildings density so they are clustered. Good example is Call of Duty 2 Africa multiplayer maps - even with many small passages and houses, it is perfectly clear if this "block" part of city is an arena or an obstacle. The idea of Onslaught is to strike where there are no enemies and to react where they are - and it implies that you KNOW it; you either have some choices (passages, like Primeval) or see them from afar (open space, like Dria).
Players don't like neither too many choices nor too few. Give them 1 passage and they complain that it's a spamhouse (see old version of MasterShower, without tunnels). Give them a map with hundreds of passages and it's a spamhouse again.
- Add more memorable landmarks that can be seen from ground-level - tall buildings, unique architecture, maybe even differently colored buildings. For example, in Spiffingrad there is a railroad that goes through all the map, and you always know if you are going parallel or normal to it, and on which side of it you are now.
- More like a whim, but I like to play maps with some background in them.
VK Playground is an arena created only for battle - and you expect to see exploitable elements there - and you have all those boxes, climbers, railings etc.
Hollon is something from another world (a shame that it's balance is bad, but I still like the visuals).
Even the cursed MTMU explains that you are in some kind of modern city.
OTOH, Torlan is something weird - you can never guess what is that tech tower doing in the middle of natural landscape.
If there is a "ruined 20th century city" setting, you expect to see some big roads, some small roads, some appartment buildings, some industrial/administrative buildings (an underground passage in Nevermore is a good example). You definetley do NOT expect a 2x2 kilometers square of copy-pasted ruins.
Verdict:
A moderate implementation of a good idea; can be turned into a nice map, but it'll require a big amount of work.
P.S.: I really thought the Opera House is the *insides* of it - all the seats, curtains et cetera, not the outsides
, i'm actually playing with the static-meshes, import them in 3dsmax, treat them for bad vertex/lightning, re-texturing and re-import into ued, ******* seams 
