This is based on my own personal experience with Sony Mobile's repair center. This is a brief summary of events that took place and is not the full story.
One day my phone started lagging a lot, so naturally I restarted it. After the restart, some of the sensors stopped working, so I sent it in for repair. A few weeks later my phone was send back not repaired because of some moisture that got inside my phone which caused some corrosion (I never take it near water except for testing). When I got my phone back I tested it out to make sure everything was fine, being a waterproof phone I put it in water (completely closing the flaps first). That's when I found out that the back of my phone wasn't placed on correctly and water was seeping in. So I sent it back to the repair center. Another couple of weeks passed and I got an email from them telling me that it was beyond economic repair, and to pay them a fee to have it sent back to me. I then called Sony Mobile and they told me that it was their policy to 'not fix phones that have a little water damage' so that's why the back wasn't placed on correctly. An argument ensued, and the case was sent up to the highest management, whom agreed with the repair center, because it could be dangerous to keep on using the phone due to corrosion. One employee told me that if I had kept on using it the battery could explode. Which is something the repair center never warned me about, so I would have kept on using it. So not only have they refused to correct their own mistake, but also put me in danger.
Long story short, if you buy a Xperia phone don't expect to get good after purchase service. They make mistakes and aren't willing to own up to it, and aren't willing to even send back a now bricked phone for free which they had a hand in causing. As huge of an Xperia fan I was, I can no longer bring myself to recommend the brand to anyone.