How do you get the clean android UI?

Long story short, first time Android user, my Lumia is gone for repairs and they've given me a Samsung Galaxy Ace. I think it's terribly slow, but I think all of this is to blame because of the old phone, and also because it's a phone they give you when yours is gone for repairs, so it's probably used for a long time by now.

I'm not tasking it too much, hardly installing apps, I just want to do one thing with it though, I want to get rid of the horrible Samsung UI. I quite like the look of the guidelines Google is giving for design, does anyone know how to get this entire look&feel on my phone? Is there a single app I should install? Thanks for any replies!

This is something I'm trying to achieve:
http://developer.android.com/design/get-started/creative-vision.html
http://cdn1.sbnation.com/entry_photo_images/7163511/n10-pdp09-googlenow_verge_super_wide.png
http://dribbble.s3.amazonaws.com/users/29114/screenshots/871796/attachments/93516/NEW_CONCEPT.png

For reference; this is what I'm stuck with now:
http://i.imgur.com/yAvOKEt.jpg

I think I'd be quite happy with this phone when I have the UI, it's really quick in simple tasks such as messaging or WhatsApp, and I really like the Notification Center, I'll miss this when I get my own phone back