Man I love the character designs in Arknights, but I really don't want to invest in a gacha game. If only its monetization model is more like Girls Frontline...
There is a free pull system sort of like GFL's (but worse), so you could play without paying and eventually get a decent set of units - people have successfully cleared almost all the content with only freebie stuff. But it's definitely a struggle unless you pay, so if you have trouble with getting tempted to drop cash on these games definitely don't play it.
I like the character designs a lot but I wish it focused a bit more on character stories. Outside of the main story cast we really only get occasional character-focused events and the lore text in their profiles. :/
The news that trickle in from players that play AK are quite worrying for me so I decided against taking the plunge: restrictive stamina system that is ironically named sanity, earlier units get power creeeped, event maps only forcing you to play a certain way, event map so janky it's obvious they didn't playtest the thing, and just the damn gacha system. I played GBF so I know I'm weak against that particular kind of model. (Thank you very much for your work on Viramate by the way m(_ _)m ) I like my cute anime art and lore, but AK in its current state sounds like something I'd best avoid. Which is a shame, because it does look very attractive on first glance.