Well Harry dying made sense, and we knew it had to happen sooner or later (3 was the most likely as thats how many films everyone signed to do originally), and Venom didnt really die.
Did you see a body?

Killing off bad guys is something of a superhero movie tradition.
The Batman movies have been notorious for this, but at least Spiderman has been pretty true to the comics source, as all the villains who have died (and I reiterate, Venom did not die), also died in the comics.
The only thing is its had to be accelerated for the movies.

The problem with this movie is the above mentioned contracts.
Although Raimi has said in the past that he wants to do 6, and Dunst has said she will come back if Raimi and Maguire return, there is no guarantee that there will be anymore sequels, and if there are, there is no guarantee it will be the same people.
This meant that Raimi obviously had to accelerate 40 odd years of Spiderhistory if he wanted to end the story how he wanted.

Look at how poor the story in X3 was once Singer left that particular franchise, despite the fact he did all the set up for it!

Nobody is disputing that aspects of this film were rushed, but I'd hardly say it was shit!