Yes, L for Android 5.0 Lollipop as Sony's official blog broke the news recently. Expect that after the update, you will have the fresh, streamlined looks based on Google's material design, new notification and lock screen, guest mode, Android for work and better storage control.
Once that your device is good to go for the update, we advise you to have a strong and reliable WiFi connection and at least full-charged phone.