I'm updating a bit my impression, since meridian made again its way onto the map cycle. Like before, I'm overwhelmed by the mapping love put into this map, from its exotic themes to the sheer size and layout.
But gameplay wise there is hardly anyone supportive of it at the moment. I can't ignore the "lazy factor" from the playing masses, but we have a vast majority of custom from any type so I can't blame our players of being narrow minded. If I could give a guess, I would say that meridian displays quite a deadly combo of complex layout, exotic gamemode, corridors fest and bad direction hints.
More precisely : the complex layout comes from the TC mode oviously, but it's unavoidable. The exotic gamemode should be simple enough to get used to, but players commonly seems to bear a grudge against TC mode, (I would say because of Hydro stalemateness). I don't mind either.
For me the most critical issues are than overall corridor layout. Some important parts of TF2 gameplay are toned down in such a layout, and many players do love balanced mix of opened and closed space. What is created at the moment is mostly surprise clash after some corner.
Finally, even if you used a fair quantity of signs, the layout on itseld does not promote a fluid gameplay. Many exits use unrothodox convolutions, and turns, and a countless number of time people driven by their instinct follow a route only to find a dead end. The central robot area of the first round is especially prone to this. TC_hydro has exactly the same issue, on a less large scale, though.
That's why, even players that would want to play seriously and use teamplay to push into the defence line, eventually give up on this, since many other ones are basically opposed to the gamemode/the map on itseld, or lost, or try solitary actions into the labyrinthic layout. The last play session was all about very early intel stealing (pyros and spies rushing into the intel room before engies are really ready). People couldn't even get used to a single round configuration since each one lasted on average 2 minutes.
I'm glad to see you're using your tropical island theme on another project. I'll try to playtest it soon and hope you'll get somehow more popular approval.