Well as you said, you need to wait for the right moment, flask is fine is you do. It does lead to situations though where you're at low health and you have to avoid several combos until one of them has an opening window long enough after it to drink. Not every combo does and if you drink at the wrong time, you're certainly dead. That's a big improvement to be honest. Estus flask shouldn't be like a "ok now you're safe" kind of thing. Hell even if you manage to drink it you sometimes die right after cause the regen isn't THAT fast so if the boss hits you for more than you healed you'll still die.
I ended up never using lifegem other than early game. Early game mostly because I'd run out of estus flasks before the boss was dead, but once I got like 6-7 charges, I never used a lifegem again(other than specific stuff like walking into lava or countering mytha's poison room). You can move around but the rate of healing is complete dogshit unless using the stronger lifegems and those are fairly rare I've found. I did end the game with like 30 of the middle ones and 80 of the smaller ones though, so could have used more definitely.
I'll say though overall a lot of the bosses were very easy. Few had really weird patterns, a lot were very standard patterns and a lot were also slow as all fuck. I guess that's part of the reason there's so many bosses in this game, a lot are just fucking shit. Some were cool though and I liked some of the variations to Dark Souls 1 bosses, like gargoyles actually made me laugh at the logic the guy must have used: "hmm ok in DS1 you fight 1 gargoyle and one more comes to help. Let's make it so you fight 2 gargoyles from the start and one more comes to help. No wait 2 more. No wait fuck that, let's make it 3". When the 5th awoken I was like what the fuck seriously? Boss was easy mind you, but still funny. What they really didn't need were bosses with adds, those were fucking annoying, especially the rat authority, that one was stupid as fuck. It's one things having adds like the spider, it's another having adds that give 50% toxic everytime they hit you and are too small to hit with a lot of attacks. Fuck that shit, boss wasn't even hard once the adds are dead but I spent most time dying before being able to clear the adds.
And they definitely should have made a better last boss. The boss for the dark covenant for example would have made a fine last boss.
