A defense supporting upgrade for horizontal decks (asset spam and the likes).
Easy to trash (2) and unique (Rumor Mill). On the other hand it's an upgrade so it can be installed on centrals as well as a remote scoring server.
The big question with this card is "when is it worth it?". Let's assume you've got 2 remotes, that's a 2 per turn discount. Most decks have at least 3 or so remotes, even if there is only one scoring server there is typically at least a Jackson Howard and a few PAD Campaigns. At 3 remotes Khondi Plaza delivers 3 for ICE. That's a decent discount. Is it enough to slot it? Probably not.
However once you get decks with 5 or more remotes the ICE savings start to add up. Being able to rez heavy ICE cheaply means you have a real shot at keeping the runner out of a server.
Since Khondi Plaza is unique though you have to choose which server you want to protect. This can be very match-up dependent. If you run a fast advance deck and you're against a shaper R&D is probably a good choice (fast advance doesn't require scoring remotes and shapers like to run R&D).
A potential issue in the deployment of Khondi Plaza is that the runner may run your server just to get rid of it. Timing the install and rez well is important in such a case. You'll want to make the install and rez coincide with the presence of a powerful ICE you can then rez cheaply. Note that you can delay the rez until you need to rez a piece of ICE (Timing structure of a run 2.3 has a non-ICE card rez window).
All in all this is a powerful support card for ICE in horizontal decks.