Spoiler alert!
I liked the concept. It must have been difficult getting so many original actors together for a movie and a script. I will not repeat all the good that others have explained so well in their reviews already. The multiverse concept was brilliant.
What didn't work for me was the excess of emotions.. Spidermen crying for little things was just too much.. Spiderman(Tom) losing Aunt May, was supposed to be emotional, but why were the other two Spidermen so emotional n crying is what I didn't get nor found it funny.. It felt like all that the amazing spider man did in this movie was to cry.. Also, you could expect immaturity from Spiderman(Tom) as he is a kid and that is how his character has been developed in last 2 movies and Avengers, but Dr. Strange seemed a little immature too in his action.. that didn't go with the mental image I had about him in my mind.