We all agree on a hard truth that most people seem to agree on about the Souls games, but here it is: the combat is very remarkable.
In terms of actual complexity there's quite a little bit going on. There's a decent bunch of depth, and the lack depth wouldn't be a problem, except the series has increasingly leaned on its action elements more and more as time has gone by, without dumbing itself down with character action mechanics such as dodge offsetting, jump cancelling, juggling or a style meter.

If you're a staunch enjoyer of the series this is where you might be flooded with memories of all the attack animations your favorite weapons has... There are differences in range and damage, and the effects on an enemy can vary greatly. They lose some health with some of the most satisfying damage/defense curves in vidya history, suffer some reliable and satisfying hitstun, and your moveset greatly affects how the fight feels and where you can attack.

In terms of defensive options the series is a a little less interesting, with the ability to block, parry, or dodge most regular attacks...Fortunately, DS2 onwards, parrying bosses is frequently super powerful, and outside of DS3, blocking is very effective, which leaves you with rolling as merely the main defensive action. When you're not rolling you'll generally be landing a few hits with whatever option you choose and then trying to preemptively move or prepare a low-profile to see if you can avoid rolling another time, and with the ability to stun and evade bosses without i-frames theres a lot more to a weapon than the animations and damage values it has

You go in, first-try the boss without memorizing the moveset, maybe you die a few times along the way, until you know the boss's moves just enough to beat it. Then you walk around them, punish at the right times, and win the battle. It's perfectly serviceable gameplay for doing it 20x in a single game!!