I hope the attachment and below URLs will help you.
I put some of my thoughts on QlikView vs. Qlik Sense in a blog post. It's a couple of years old, but is mostly still relevant:
It is true still that QlikView has the ability for a skilled developer to create something amazing by getting under the bonnet and tweaking things. Some of that ability to customize is not there out of the box with Sense. What you do get though is a much more modern and responsive UI. Learn to live with (and love) what Sense gives you out of the box and you will find it is a brilliant product.
If you really need to customise Sense this can be done through the API and with mashups. This does require more work and a different skill set though.
Hope that helps?