I'm sure you've read this before, but it really depends on the individual bird. Just like people, they can have widely varying personalities. I'll just state some personal experience and a bit of stuff I've learned while reading up on Eclectus parrots.
I've had Coda for a little under 5 weeks now, she is 9 months old and she is an amazingly cool bird. She settled in within a week but was still bitey and apprehensive, she really started trusting me in week 2, began exploring my room at week 3, and now in week 5 we are best buds; just earlier she fell asleep on me while I scratched the back of her head. She's adapted so fast and has been totally fine with meeting heaps of new people - instantly stepping up and sitting on their shoulders, eating from their hands, etc. This includes my housemate's 6 year old daughter - who she is fine stepping up on to and interacting with.
I've taught her to step up/down, fly to me/back to her perch on command, spin in a circle, and wave when I say hi. She's an extremely fast learner and is always keen to hang out and play and learn new things. It took her a while to get used to toys, but after slowly introducing them she is fine with new things being added to her cage and doesn't get aggressive about it any more.
In addition to that, Coda is at the tail-end of her first moult, as well as entering "eclectus puberty". This apparently starts at around 9 months, and has the parrot exhibiting wild mood swings where sometimes they are happy to interact, and other times they may get extremely touchy and unhappy and squawk loudly for seemingly no reason. This can last up to a couple of years depending on the bird, but they do grow out of it.
Eclectus parrots in general are very quiet, stoic birds. They're considered one of the most quiet birds you can own. They don't have random squawking fits like pink and greys, and they don't blast your ear-drums with brainshattering squawks (apart from the aforementioned puberty phase). Coda is silent most of the day, unless she's playing or I'm talking to her, in which case she lets out some trills and squeaks; and she grinds her beak when she's chilling out. This is great if you value quiet, but requires caution: if eclectus parrots get sick it can be hard to identify the symptoms, as they do their best to hide them. In addition to this you need to take note of the many things that can severely harm or kill your parrot - certain foods like avocado and chocolate, products like non-stick pans, natural gas, petroleum based rubber, etc.
The diet is definitely more difficult to maintain than many other birds - as is with most large parrots, as they require raw fruit and veg daily; which need a thorough wash before serving. They can't rely on just seeds and pellets, and they can be a little temperamental about what you feed them - some days they may like corn, other days they might throw it on the cage floor.
But like I said before, it depends on the parrot, where it lives, the enrichment in its cage, the quality of the time you spend with it, and a bunch of other variables. We can generalize, but only to a point. The main thing to take away is that they are a big commitment, they require a lot of time and energy, and you need to regularly interact with them.
Hopefully that answers some questions for you!
Here's some random photos of Coda if you feel looking at some eclectus goodness.
