The gameplay loop is fun. It's very similar to Deep Rock Galactic, which is endlessly replayable because of the gameplay loop. Even after you unlock all the weapons and skins, it's still fun to play. If you like this type of game, you'll like it for a long time. Each map is different, the layout is randomized, and each planet is unique, with different biomes, visibility, day/night cycles, smoke/haze (which impugns on you and your enemies ability to see), and various modifiers which affect mission playstyles. The world is highly destructible (less so than Deep Rock Galactic, but that's a special case): buildings and cover can be destroyed; trees and foliage actually block shots until they're destroyed; dead bodies leave cover for enemies/friends behind them; and large explosions actually leave craters in the ground which can provide cover in prone position.

The game is also funny. You can play it seriously or lean into the humor. It can also be really wholesome, as you have player interactable emotes (like a hug), and the entire crew will often hug and/or salute each other before a mission extract.

It's a lot more complex than one would normally assume. Some examples... Reloading a new magazine gets rid of the ammo you had in the old mag (which doesn't magically reappear in your inventory like in almost all other shooters). Reloading with 1 round left in the chamber is faster than with an empty mag (this is a real world gun thing, if you know, you know). Reloading is staged so if you're interrupted mid reload, like when you have to dive to avoid a bug or a missile, your reload time (and the animation) is shorter afterward. Glancing hits with grenades can ricochet and some anti-armor guns do more damage with direct on hits, and can also ricochet off the heavier armor with glancing hits. There's crew fed weapons (which need to be buffed to compete with the railgun, but still). You can play it more stealth like if you want to (and with team mates who will cooperate), especially with the right armor and being mindful of patrols. Laying prone reduces damage from surface explosions. Crouching and laying prone increases stamina regen, reduces recoil, and reduces your sight picture (aggro radius) to bugs. Light sources (like lamp posts) increase aggro radius, but can also severally interfere with your ability to see enemies through the glare, but they can also be destroyed. And (once they figure out the weapon balancing), there will be a lot of leeway in build options.

Given the history of Helldivers 1, and what the devs have said, there's also going to be quite a lot of future content for the game, in terms of enemies, missions, planets, guns, stratagems, armor, and cosmetics.

I'd also like to add that you don't have to spend real world money to get certain cosmetics in the game. All game cosmetics can be earned through playing the game.

If the game didn't have the rootkit, it would be 10/10. With the rootkit, if you're willing to accept it, the game is definitely worth a buy.