I finished yesterday. TLDR
santino27 is right, it's a decently entertaining game that you'll most likely never play again. Buy it on sale.
All my reservations from earlier in the thread turned out to be correct. After Chapter 16 or so, there's nothing new to discover. The tech tree is designed to be fully unlocked by midgame, so no tension in development or CnC in terms of building your army. No new units or types show up after Chapter 15. Some (not all) of your main character units auto-promote later in the game, but with the exception of Thicc Gr1l, it's not really exciting, visually or mechanically. You'll have plenty of opportunity to make a large army to your taste (most missions after Chapter 20 will allow you to deploy 15-20 squads), but there's no incentive to do it.
thesecret1 addressed why: there's no challenge.
If the stuff I read earlier in the thread re: bitching by players about not being able to grind is true, my faith in humanity continues to plummet. There is zero need for grind. None. Never did I feel underpowered or threatened. Rather the opposite. I did lose squads occasionally (in contrast to TS's play :D), but only because I didn't take time to create well-made compositions/formations, and couldn't be bothered to follow good tactics. I felt no reason to care about a squad or soldier getting wiped out, because after winning the map they were right back in my Army screen, ready for the next mission. Zero stakes, zero tension. And because you effectively never lose a man for good, by Chapter 20 or so every soldier is max tier, and brand new hires only take a couple Arena runs to bring up to par.
Late in the game a small bundle of side-quests are dumped in your lap with little explanation. You can complete them or not, doesn't really matter. Two of the missions' rewards would be pretty cool in a game with any sense of threat. Not so much here. In a couple side-quests and some of the later mainline missions the objectives throw some curve balls with potential, but it's too little, too late, and not difficult enough to excite any emotion or attachment. The game is a foot wide and an inch deep.
The story sort of loses focus after the climax, with characters taking actions and saying things without rhyme or reason. One that really stood out was Lysander screeching at Jedediah about how awful the Nephilim are, how he's plotting their overthrow and death, and how much he especially loathes Diana. Two missions later he's begging forgiveness and has seen the light. Why? Who knows, not me. All the non-Nephilim characters end up turning against them with Lysander, yet at the end they're once again singing praises and mea culpa-ing. If this is the caliber of a new republic's leaders I fear for their future. Heroes become villains become heroes again and I didn't really care about any of it. Meh.
I'd probably rate it similar to some of the quality Flash RPGs I've played in the past; good fun for awhile (maybe even a long while), not really worth a lot of attention and I'm not going to bother playing again once I'm finished. What's the point?