And format it with several bullet points:

1. You know how EDA/ETA is being called "Hyldrin/Dante meta"? Yeah. Icebind is literally just "Dante Meta". Any sort of supposed "difficulty" to survive for the whole team altogether is entirely trivialized via Overguard spam - just bring good weapons/frames to deal with the actual killing while Dante keeps everyone alive. And while yes, there are options like Oberon to provide everyone with invulnerability too, along with other benefits, as well as Trinity and several other sources of various layers of damage-reductions(like Folie's statue too, giving up to 90%DR)... Still, nothing comes close to sheer comfort of Dante making everyone immortal 24/7. Just gotta have a compitent Dante in your team and it might as well be you, of course. So yes, imo, Icebind = Dante meta to cheese through it. Though, inb4 Dante gets nerfed hard - either in general or specifically through modifiers (like those EDA/ETA shield modifiers that were clearly targeted at Hildryn). And yeah, I know, there's already one modifier against overguard. It tickles, at best lul;
2. Having no matchmaking and opting for Yuvan peak chat "LFG/LFM" spam in order to get a team simply is a waste of players time. Came to Yuvan Peak. Sent out "LFG". Got invited as the last needed person for a squad. Nice! Did one run with the 1st team. Everyone disbanded after 2 people leaving since it was their last run. Decided to create my own squad, invited two people. Then we spent ~15mins looking for more people, with most of the time spent finding that ONE LAST PERSON. And together with us, two other teams in the same chat were "looking for more" as well, not willing to disband and combine. We are all still total randoms, like in rando matchmaking in the rest of the game, so what's the difference? Only a waste of time;
3. Ping issues. Having 300+ ping is definitely not optimal, nor enjoyable gameplay. Yes, we managed through it, sure. But again... Matchmaking like in the rest of the game would handle this issue better, filtering high-ping host/players out, no? Manually searching people up kinda eliminates the automatization of ping limiting and wastes everyone time even more.
4. The rewards are... not worth it at all? I got those 3 new riven splicer thingies(ok, whatever, I suppose?), a couple of rivens(into the pile of untouched veiled rivens), a tiny amount of Kuva(like, 30k something fot 3 runs combined? That's like nothing), a 3-day affinity booster and a single blue shard... Seriously now? It's absolutely not worth wasting your time on any of this nonsense, especially considering the wait time on looking for group and potential fail-restarts, prolonging the run. Doing Kuva Survival solo would be more profitable than that, in terms of Kuva. And the rest of the reward pool does not seem worth either. And Riven thingies are only worth for gambling addicts... I mean riven traders. Unless rewards are improved, I do not see myself doing this mode again any time soon, not even as a weekly "one-and-done";
5. Survival seems to be the cheese way to go. Makes it easy to focus on that secondary objective, since there's no need to protect any "main" objective. We tried Mobile Defense, twice. Both failed. One time, the secondary objective popped in another room, ~100m away from the main objective. We learned the hard way that splitting up between defending main and doing secondary ~100m away is not viable. So, on 2nd run, we waited out the completion of main objective, THEN started the secondary - which popped up right next to the main this time, in the same room, like ~10m from the main. But guess what? We still failed because on the 2nd secondary (which ended up being a chest with cyphers), one person going into operator to dodge jade light made their warframe DROP THE CYPHER, which then proceeded to DISAPPEAR, thus leading to objective failure. This means that if you wanna do and focus on the 2ndary objective - you literally have to sit out the main first, as you won't be able to split attention. Especially if it spawns far away(which happens) instead of nearby. So we just went for another survival and easily done it without problems;
6. On top of going into operator dropping the cypher in the chest-unlocking secondary objective, I wonder how many more "bad interactions" there are with warframes and their special modes? I am talking about situations like the Entropic Eximus being heavily "anti" Jade, Hildryn, Oraxia and other frames with traversal modes, forcing them into one specific gameplay style. Titania comes to mind - she can't hold a cypher (again, for example) while in her 4th flight mode, as she's tiny, right? So... Good bye Titania in this mode, I guess? Being forced into grounded mode for a side-objective makes her not an optimal choice for this. What about other frames, I wonder? Do they also have some other similar negative synergies?
7. Entropic orb secondary objective "circle" has poor visibility in tile-sets with uneven floor. We had a Kuva fortress tileset and the orb spawned in one of the courtyard pieces where there's regular dirt and rock floor instead of flat surface. On top of that, we had Oberon spawning bushes everywhere. This made seeing the circle on the floor where you need to stand in one specific quarter not to get hit literally near-impossible. Because one half of the circle was pretty much entirely obscured into an uneven floor, the other that's visible - partially covered by Oberon's bushes lol. Either prevent it from spawning on uneven flor OR, even better, have that circle be slightly elevated from the floor to prevent negative synergies with something like Oberon's bushes;
8. Minimap on the top left being blocked/covered by 6 player icons, forcing you to use the big overlay map instead to see things. Most likely just a UI bug, as I've seen this happen in regular 4-teams too and in other modes.

Afterhtought

And at the end of the day... This really isn't any "new mode" to begin with. It's just the same exact regular starchart missions we've been doing for years, but with EDA/ETA modifiers nonsense slapped on top. We're just not locked into Entrati Labs/Hollvania, like with those two. And on top of that, we got no matchmaking + real bad rewards pool?

Did they really spend all this time developipng... this? And even had to delay it?

How many people were involved? One mainline coder and two newly recruited interns, thus taking them this much time, with a delay even? Like, I get it - their main power is currently focused on Tau stuff, sure. But no way this sort of "mode" takes that long to develop. All of this is just existing code that needs to be repurposed. Basic starchart missions, just levels bumped up a notch? Code exists - just reuse it. EDA/ETA modifiers? Code exists - just reuse it. Those secondary objectives? In one way or another, all of the mechanics I saw in these three runs literally exist in one way or another in the game, as part of other game modes and mission types. Again, code exists - just reuse it. No way this final result took this long and a delay. It's not a "new mode", it's just a combo of reused assets, for poor rewards.

You can now downvote me all you want.