Honestly, I liked it much more than the first Avengers film myself. I see a lot of folks criticizing Ultron not just being more logical/ruthless and quickly coming up with some fast scheme to kill everyone, but remember, Ultron was an A.I. created by Tony Stark for the purpose of 'saving' the world, and it came across as being a reflection of Tony's mind, and as a result, was somewhat conflicted; and a big point was that he wanted mankind (and the planet) to 'evolve' - so what better way to accomplish that then having another asteroidal extinction event? I loved that they didn't just m make Ultron a 100% cold/logical killer. It actually had issues it was working through as it came to terms with its sentience.
I thought all the character moments were good too. We got to see more sides of everyone, and they delved more into Black Widow's origin, etc and it was nice to see a real nod to her original origin from th comics although, again, with her birth fixed in 1984 - it's still a mystery to me how the KGB would be involved as by the time she was 'of age' ity no longer existed.
Again, I guess everyone goes in with different expectations, but I really enjoyed this one more than the first, and loved the character interactions and conflicts. the point where the Scarlet Witch KNOWS what Tony will probably do with Ulton's casket, and the rest of the team showing up to stop him, (and honestly BOTH sides had a point - it wasn't back and white); and in the end Thor showing up to do what he did was great.
One of my favorite little character bits was the fact Thor's Hammer did 'giggle' for Captain America (and the look on Hemsworth's face as Thor was great when that happened.)
I was never a fan of 'The Vision' character from the Avengers comics (I ered them from the mid 1960ies into the late 1970ies), but I have to say I really enjoy the tweaks they did to the character and his origin with this film, and I hope we'll get a chance to see more of the character in the MCU. He' not just your garden variety human built android using a refurbished body from the 1940ies (he was originally made using the original 'Human Torch' of WWII vintage which was itself an android); but now he is more a cybernetic artificial life-form that combines human, alien, and Asgardian technology.
Again, everyone has different expectations, but I gave this film an A+ - and it shows what can be done by people who respect the material and don't try to change it just for perceived marketing or to fit a 'formula' for a film, etc.