If I want to get into the game, how rough is it to be a free to play player right now?
In addition to what others have said... I think an important thing to know is that, for better or worse, the way the game's difficulty works means that you really shouldn't hit a sudden wall where you're underpowered for story content. You have a player level ("adventurer rank") and what range of ranks you're in sets the scaled difficulty ("world level"), changing the level of enemies in most of the game (beyond specific non-scaled challenges). You are effectively gated from upgrading too far ahead of the difficulty - not only can you just not upgrade characters/weapons past certain points at lower ranks, you need higher level enemies to get the drops to upgrade them - but in return most fights are always going to be pretty fair for you.
I do believe just starting the later main story chapters is actually gated by reaching certain adventurer ranks, though. I don't
think it'd be that hard to naturally hit those ranks as you progress through it, and they even re-balanced the requirements to be lower with this update. I'm assuming that it particularly should not be much of a problem due to that change. It's just personally hard to judge how long it took to level based on how I played it (essentially stockpiling exp at points where you need to manually advance your rank, which would not be necessary anymore since they added an option to turn down the difficulty by 1 world level if needed), so I can't tell you if you can truly mainline it or not.
Meanwhile, regarding things that might be concerning you as a f2p player (as a f2p player myself)... you have missed free resources from events, but it should not be too bad to farm those if absolutely needed, you might just need to do a little farming on specific days of the week when they're available, I guess. Compared to other gacha there's not really been notable event exclusives you've missed, mostly just those free resources. We had a couple specific event-exclusive weapons and some free 4* characters given out, but the free characters are just regular gacha ones. Though on that note, I think the biggest thing that differs from other gacha I've played is that most of the gacha characters are actually
completely unavailable when their banner isn't around - the permanent pool of 5* has not been touched since launch, so beyond that initial group you can only get a 5* on their specific banner. That can obviously be pretty limiting for building teams as a new/f2p player - but I only have 2 5* and 1 of them is a permanent one, so I can say that while I do rely heavily on those 5* you can definitely be totally fine without the ones you've missed. You should be able to build a good team around anyone you get and do just fine. And, well, we're getting close to the game's first anniversary in a couple months, so I'd be kinda surprised if we don't see some rerun banners that will let you try for older characters you want anyway.
