This is what made me buy it Day 1

All Nintendo games you have played == All Nintendo game (At least I doubt it).

If your argument is that all Nintendo games are good, I kinda don't quite agree with that lol. Devil's Third comes to mind. And there are quite a few 3DS games that haven't reviewed well (Like "Dedede's Drum Dash Deluxe!" or "Lego City Undercover: The Chase Begins!" or "Steel Diver" or "Pokemon Shuffle the Candy Crush rip off") and if you're gonna say "There are some people who enjoy those games" same can be said for nearly every game there is.

Just say something like good games don't deserve to bomb

I still have to get this game...
My finances went a little crazy around the time this game was released, but the light at the end of the tunnel is getting brighter, so I'll be able to make some unnecessary purchases soon...
But I'll probably get Splatoon first...

I have too large of a 3DS backlog to play it just yet. It will probably be one of the last few games I get. It looks decent though.

well I think the only Nintendo game I have yet to play is Style Savvy and some japanese exclusive games, so close enough

You don't tell me what to do

Having talked to people that played both this and the Valkyria Chronicles games, apparently Codename STEAM fails to do anything as well as the Valkyria Chronicles games, and comes across as a very subpar experience after seeing the gameplay elements it attempts done well elsewhere. Disappointing, really, but hey, there are three good alternatives available, even if they aren't on Nintendo systems and one requires a fan translation patch.

The demo convinced me not to buy it. The enemies look bland to me as do the environments. The steampunk idea is awesome, but I absolutely hate the characters. I just think the premise is so stupid. Not even in a funny kind of way. Valkyria Chronicles needs to show them how it's done. Or Xcom.

It's a bit 'niche' and they didn't market it well so that is why it bombed

In the end, it was just very poor marketing, that and it's not the most appealing looking game for everyone.

I thought it was exemplary.

The demo convinced me just enough to get it. The beginning is pretty bland, the problem being the bare squad you start out with. But, it took quite a turn for me once I got past the small hump and got to see all the game had to offer. More characters with different weapons, different weights for different Boilers, and plethora of sub-weapons gave a lot of options. I was especially a fan of the Fire Emblem characters I got from the amiibo (all but Lucina. Someday...). Setting up what units to use and what equipment they should get for different situations was pretty interesting.

I like planning ahead and getting the jump on enemies. Like in one mission: the goal is to get to the end while keeping the enemy away from it. A certain scientist character's main weapon is bait that all enemies get attracted to, turning their attention towards it, and having them all go for it on their next turn. It was satisfying just picking them all off with explosives and made getting all the collectibles a cakewalk. 

A few things annoyed me, like enemies' overwatch being WAY too all-seeing at points. Also wasn't a fan of shots just outright missing when the reticle is right on top of them, the hitboxes being made meticulously accurate to their model's. That made the tiniest spaces where shots could miss and I am flipping infuriated every time it happens.

I believe it didn't do well because of Nintendo's marketing. Being completely honest with ourselves here, Nintendo left this game out to dry. It got nowhere near the marketing push that Splatoon had, heck, even being overshadowed my Majora's Mask 3D and Xenoblade 3D at the time. It's also just a really weird game. It's a shame too, I thought it was something special.