A much maligned EDF game. The best of Yuke's lineup, but doesn't qualify as nearly good enough to recommend it at full price.
Assuming it is on sale, however, it might be worth it. It's different enough from the main games that while I wouldn't advise buying it before any of them, I wouldn't say buy it last either, it can be a good palate cleanser between 5 and 6's ridiculous amount of missions for example, as going straight from 5 to 6, including the repeated missions from 5 in the later, would honestly be too much of the same thing.
So, first, let's go with the flaws, to get them out of the way:
-The maps are small. This might be less of an issue if the mobility of certain gear weren't so effective and if enemies didn't gain so much speed on higher difficulties, but you will eventually notice that small map size as it is, and the DLC's attempts at giving you the main series' mission length and enemy population makes this intolerably awful when combined with this game's reliance on 'this many times per mission' mechanics.
-Stuns. While people overestimate the number of hard stuns in this game (the main series has more, you can at least still move or use up energy to get back control in this game), there are plenty of soft stuns that will cancel some key actions, like item use or the Prowl Rider gear's grappling hooks. Namely, any amount of scratch damage whatsoever will cancel those. Drones are the absolute bane of every gear but Heavy Striker in higher difficulties, with their constant firing of near-hitscan projectiles preventing Troopers and Prowl Riders from using their bread and butter abilities, and rapidly draining the squishy Jet Lifters of their health.
-Many weapon lines just have dead stops in their progression at around the level of the first difficulty after Hard. This makes replaying the game a lot less enjoyable than it could be, combined with the earlier flaws, which is especially a problem in light of the small mission list. In addition, you can't test weapons before buying them, and you have to buy them (without being able to make an informed decision, with fairly limited cash and resource rewards), though on the other hand once you've acquired a weapon, you won't get turned off from attempting to use it further because you happened to get it at an unacceptable quality level that makes it utterly worthless as will happen most of the time you first acquire a new weapon in EDF 5 and 6, so it's give and take there.
-The NPCs are absolutely worthless, literally firing in random directions and failing to even distract the enemy, which is especially puzzling given the decision to give you a squad of named characters who are constantly chatting through every mission. Similarly, multiplayer operates off a lives system with respawns after a brief opportunity to revive people rather than failing the mission if everyone is dead simultaneously, and completely removes the NPCs.
So, that's a lot. You can see why the game doesn't exactly have the highest reputation. And yet... There's a lot that's actually pretty decent here. For example, there's the weapon variety (when it's not being damaged by the fact some weapon lines hard stop halfway through the progression) is surprisingly large for not having the series large spread of returning weapons each game. You should seriously consider the pros and cons of the various reload mechanisms for example, with 'passive charge' and 'secondary reload' weapons requiring different playstyles from active reload or static reload weapons, for example. Similarly, damage type, including the elemental ones, are a big deal and packing an ice or electric caster can stunlock the enemies, including minibosses and even the DLC's boss for quite a while. Swords meanwhile have a lot of interplay between their rapid-fire, high melee DPS and their powerful long range charged burst strikes that can increase your air time, but that means you have to consider whether you want a sword with a strong charged attack and low ammo, or a high ammo, quickly reloading one with a mediocre but swift charge.
The consumables you can pack similarly can make a massive difference. Do you pack ice grenades to stop one wave of troublesome enemies in particular? Turrets to protect you from weak ground enemies from early waves while you kill drones? Or do you pack reload-boosting drones to spam high power weapons with really bad reload times? Defense boost and regen drones to wade through crowds of enemies fearlessly with a melee weapon and buff any player near you? Air strikes to eliminate a troublesome wave instantly?
This is especially important for the Trooper gear, which effectively serves as the Air Raider of this game thanks to its significantly larger budget for such support items that do not need to take up proper weapon slots. Unfortunately, lower difficulties don't provide you enough rewards and challenge to justify paying the price of those consumables, but in higher difficulties, your choice of those can serve as a major part of your skill expression, and this includes the once-per-mission Overdrive mechanic, which massively buffs your reload speed, gives you infinite energy for your Gear's ability, and even provides you with the bug-riding ultimate ability for Prowl Riders in particular. A large part of the game's scoring system is timing it at the most heated point of the mission to tear through the enemies, and when it works, it really does make you feel powerful. Odds that would be insurmountable in your standard state become a breeze with a buffing drone and an overdrive.
Speaking of, the mission variety is surprisingly high, including legitimate defense objectives, something the main series lack. Not all are good: the mission where you protect a city from both meteors and enemies that destroy buildings is kind of bad, considering a lot of your own weapons can cause tons of collateral damage... Especially the ones that kill multiple enemies quickly enough to get your eyes back to the skies. But racing against a rebel faction for drops as you defeat them or defending a central objective can be quite interesting, along with missions that punish careless shooting.
The ability to use any weapon type as any Gear seems like it would be less interesting than the main series' class-based weapon picks, but the same weapon can legitimately perform very differently for different Gears. Jet Lifters absolutely love any weapon that can increase their air time or even maintain their horizontal momentum while completely cancelling vertical momentum. They can also maintain charge while moving quickly, giving them an affinity for charge weapons. Heavy Troopers dual wield most weapons, doubling their damage, but somewhat worsening reloads. Troopers can carry enough consumables to enable some powerful strategies with some pretty flawed weapons that would otherwise require extremely niche situations to use. Prowl Riders meanwhile serve as a counterpart to Jet Lifters when it comes to swords. They lose momentum too quickly off their grapple to use the charged attack without becoming a sitting duck most of the time, but have a strong affinity for the standard, rapid-fire melee considering how easy getting there and then back out is for them compared to the low-mobility options.
All this to say, there's a surprising amount that goes into picking your gear, weapon, and your consumables for each missions, and even moreso in multiplayer where picking items that help your allies and coordinating who favors stunlocking enemies and who spams damage can quickly make a hard mission much easier, and all that can be genuinely quite fun... But you have to get through some noticeable flaws first, and you shouldn't have to. But there's too much that's good to just ignore it entirely because of those flaws either.
To reiterate: Only recommended on sale, after one of the main games. But don't dismiss it out of hand.
