The new input form is less interactive and offers a worse user experience. With the previous send button, I felt the message being sent, but now there's no satisfaction at all. I really liked that animation. Also, the way the form was highlighted when clicked was cool and very pleasant - please add at least an option to choose. The new form isn't bad, and the new chat page is especially great, but the change in the send button and the removed animation made me sad.
So I need to get used to the new design, but you've simply eliminated the tactile and visual interaction with the interface that I had before. You can't imagine how great it was to press enter with the previous input form.