Share your experience!
Hey, I just upgraded from my Xperia Arc to Xperia Z1 two weeks ago with my mobile carrier's early upgrade program ... otherwise I am still stuck with it till April 2014.
I am using firmware 14.2.A.0.290. How do I remove or disable Google Now by long-pressing Home button? It is driving me crazy.
You cannot remove that,it is default.If you need the recent apps task manager double tap home.
Do not believe him. You can disable it with a small and simple app. (Kudos to the person that created it and downvotes to google/sony for not giving us an option to get rid of this annoying, gameplay-disturbing feature)
Install this: https://play.google.com/store/apps/details?id=com.AdrianCampos.googlenowswipedisabler
Enjoy 
You can disable the annoying Google Now feature by, disabling the blue colored Google App. To do this go into your Setting -> Apps -> scroll to the tab ALL -> scroll down until you find Google App -> click on it, click Disable, done. For any reason if you want it back on your phone, do the same thing but scroll over to Disabled Tab, and this is where you can reinstate it, if you like. No need to download any additional apps to do this.
Download the Swipe Up Utility - app. Then you can choose what long pressing home button shuld do. You may choose "do nothing", or start another app.
PS: Use the "pro" version, which cost about 1 EUR.
https://play.google.com/store/apps/details?id=com.AdrianCampos.gnsddonate