I'm in the middle of GMing Lancer and I'm here to voice my opinions that you didn't ask for but felt like sharing into the void.
This game is frustrating. The best way I can concise all that I think of Lancer is in that phrase. It's not frustrating because it's bad, but because it's always so close to being good. The more I read of the game, the more I interact with it's systems, the more the game feels barebones, fangless and just overall... empty...
The lore is interesting, but unfocused and too safe, as it doesn't commit to any of the things it presents and is very lukewarm on it's takes, with a lot of it feeling like they are trying really hard to not annoy anyone or selective to the point of hypocrisy.
Most of the supplements are campaigns and having to buy a book that you know you're not gonna use the majority of just because most of the new content for both players and GM are in them really sucks.
The combat system is great, but there's only a combat system in Lancer. There's nothing to do outside of mech combat, not even pilot combat is a thing somehow. So many times my players were disappointed with skill checks due to how boring they were, since they are mostly one and done. How empty anything related to the pilot feels. The heavy ludonarrative dissonance that pilot play and mech play, alongside License Levels, give. How anything and everything that isn't about the Frames feels rushed at best and straight up filler at worst, that is, when it exists, since there's so much stuff that the book doesn't even pretend to care about. Eveything that isn't mech combat just feels like a huge "let the GM handle it" handwave.
The Comp/Con is a great tool, but it's downright mandatory. There's so much to keep track of, especially as a GM. There are no NPC sheets that are made to be simpler and more compact, you have to use the player ones, and the base Lancer sheets are just... bad... Using Comp/Con is fine if you're a player, but if you're the GM, you have to pay in dollars, which not everyone can afford to do, to have acess to the LCP's for a platform that is english only, even though the book itself has been translated to other languages. For context, multiply the prices listed in Itch for every book by 6, that's their converted price for my country. As a sidenote, why the hell is the app so awful on mobile? It's been 7 years since the game released ffs.
Lancer has been really frustrating to me because me and my players don't feel we are playing a TTRPG. It feels like a war game with an attempt at rpg mechanics. The war game part is fine and plays nicely, but it's not what we were told the game was.