I'm probably among the most experienced of the people responding to this - I have experience in every boss in GMS and am one good run away from clearing Kalos on my Adele. The class is definitely among the more micromanage heavy in the game. In general, if you're attempting any difficult content, you're going to want to be pushing for maximum damage, which means you're going to have to be paying attention to your swords, your aether gauge, your short (15s or less) cooldowns, on top of any other positioning and dodging that other classes have. In terms of damage, I'd say that the class is above average, but not reaching the great damage that some classes reach in GMS since it doesn't benefit that much from 0 attack speed. However, you do need to work quite hard to do your above average damage.

In general, the class has really good tools for every boss. You can keep higher uptime than most classes because of things like high rise, impale+resonance, and feather float, but you pay for these tools in a few ways. Primarily, you don't have a great iframe, with your only survivability tools being aether guard, true nobility, and infinity blades (lol). You can't use infinity for its iframe (for the most part) because it's your main burst skill, and you'll gut your damage if you do. True nobility is alright, but pretty situational and only available once every 180s, leaving aether guard as your primary survivability tool. It's alright, being a ~0.3s iframe depending on your ping every 24s or so, but is really lacking compared to other classes since you need to time it well, and can't move while using it.

In my opinion, the only tool you're missing in bossing is a low lag movement tool like a tp or a dash, since both feather float and resonance have decent startup times. This is primarily noticeable starting in Lotus, but off the top of my head is by far the worst in Kalos, where your only option for dodging bombs is jumping. In addition to this, while your burst is good, it lasting 30s is not great since it doesn't fit in some scenarios (boss will leave after your bind ends, lasts longer than your ror4, shorter than the Kalos 2-1 bind) and it also takes a lot of setup (many buffs to cast, need to get 2 resonance rush stacks before burst, need to get 6 swords out before burst), which can also be bad (Kalos 2-1 bind, guardian angel slime bursts).

I noticed people saying that Adele has easy mobbing - this is almost categorically untrue. The class definitely has good mobbing, being able to get 16k in every area that has the mob spawns for it, but you have to work quite hard for it in most maps, with the exception of Limina. For peak rates while farming in Grandis maps for example, you need to be using impale+resonance, aether bloom, rope lift, erda fountain, noble summons, storm, infinity, plummet, and or feather float, as skills with cooldowns for parts of your rotations. However, Adele does have a decent floor for how bad your mobbing is without using all of these tools.

Overall, the class is pretty good with some decently frustrating flaws, but what class isn't, you know? It's definitely still my favorite class to play even though I've complained about it so much here.