So uh, here's some thoughts (haven't been able to get on today, so this is just from shooting Octolings on it in single player, and thinking primarily about Splat Zones because I pretty much only played Ranked over the weekend, but still):
It's really big, though that might just be the really square-ish-ness and having to go through it by myself (with Octolings slowing me down) making it feel large (though I have seriously gotten lost on this map, so...).
Those catwalks are an interesting addition, might make it easier to get around (though you can't ink them and fall through when you squid, so maybe invest in Run Speed Ups), and they're an easy way to get into that center area, could be a good sniper position up there if you put some Ink Saver Mains on. Not a safe sniper nest at all (you can shoot through grates, if I'm right), except maybe that platform in the center where the catwalks connect (but that might not be as useful to hold), but a useful one if you can keep it (might be even more difficult to hold than Blackbelly's tall center platform).
Not surehow Chargers'll do here: on the one hand, those catwalks look to be prime real estate for snipers (excepting the caveats listed above), but on the other, they might have a problem around the edges. Staying on those catwalks might be necessary for Chargers, but if they can pull it off (there are platforms connected to the catwalks that can be inked, so holding those will probably be a good idea), they could hit most of the map.
Can't call it for Rollers either, since getting sniped will be a pervasive problem, but being able to ink large areas quickly should be a good thing to have, and hiding behind corners will aid ambushes imensely. Each particular Roller also brings something unique to the table that could be helpful: regular Splat Roller has Suction Bombs, which could force opponents out of hiding and even splat unaware enemies (its explosions are fairly large, if I recall correctly), and though the square-ish-ness of the map makes just firing the Killer Wail in a direction unreliable, you could aim it at the catwalks to force snipers off. The Krak-On Splat Roller, on the other hand, has Squid Beakons, which should be useful on a map this large (put one in the center for if your sniper bites it, for example), and the Kraken, which can do nothing about the catwalks but can get around the sides of the stage quickly, and maybe even splat people in the center too. On the third hand that I wanted as a kid, the Dynamo Roller is quite sluggish while rolling, but it could be a great sniper substitute/supplement up on the catwalk with its huge swings, and dropping a Sprinkler could be helpful too; finally, having Echolocator could be really useful on a map this large. On the fourth hand I also wanted as a kid, the Gold Dynamo Roller has the same strengths and drawbacks as the Dynamo Roller regarding swing range and slowness and sniper support/subbing, but has Splat Bombs to force enemies out of corners, and Inkstrike lets the roller player help teammates anywhere at any time. Maybe they'll be terrible here (this chance goes up greatly if opposing snipers run amok IMO), maybe they'll be great, I don't know.
Conversely, I'm pretty sure I can call it now for Inkbrushes. They'll be useful, since they can get around quickly and leave an ink-trail for their teammates to follow, and they can ambush people around the edges of the stage (hiding around corners to swing at people passing by gets me splatted plenty of times on Port Mackerel, so...), but they have no place on the catwalk (can't ink grates, so they're no faster than a normal Inkling on those) so they have to take the long way to go anywhere quickly. Still, they'll probably have at least a support role.
Shooters like the Aerosprays should suffer due to the stage's hugeness, but I could see guns like the Gals and Splattershot Pros being great here, especially around the sides. Squelchers could do that too, or maybe they could take up a sniping position on the catwalks (especially Custom with its Burst Bombs). Blasters should get great mileage out of ambushes (and destroying people on the catwalks, if they get close enough), but might have to shadow someone else (Inkbrushes, for example) to get around in a timely fashion (due to the combination of size and not being particularly good at covering turf). Splattershot Jr. should retain some use, between the Splat Bombs for checking areas and the Bubbler for winning firefights (or at least forcing retreats); not sure about Custom Jr. though (Disruptors might be useful for immobilizing foes for easier sniping, and Echolocator should be amazingly useful on this map, but I'm not sure giving up Splat Bombs and Bubblers is worth it). Splattershots (normal and Tentatek) should be alright here.
Overall, I'm gonna love it here. Tomorrow.
Also,
@AstralSpirit DUDE. HOW.