It is hard to look at the overall system and say yes this is too complex or no this is not complex enough. Different people interface with the system from different angles.
From the character design angle I don't like class features at every level. They seem to me like they are hardwired mini-abilities. I would do class design differently. Give them their main schtick and then let players buy into complexity if they want to. So classes, are pretty straight forward though. The only complexity is the class features which add a lot of little fiddly abilities. about the same as 3e, more complex than 1e or 2e.
From the combat side I think advantage/disadvantage simplifies things in some ways but also makes them a little more complex because modifiers still also exist and so you have to determine if it is a modifier disadvantage or a disadvantage to the roll etc. With time this will be ingrained. But at least initially it will be a problem. Also there are less conditions, not because these conditions dont exist but because they become special conditions in the rules or under the spell. I would like to see these pulled out of the rules and referenced. Encumbered, boom look up what encumbered, asleep look up asleep on and on and on. More simple than 1e, 2e and 3e.
Monsters, xp, and dungeon properties. These seem pretty straightforward for the DM. So more simple than 3e, more complex than 1e and 2e.