Screen is great sharp and colourful. I know the Tab Z hasn't got the very best chip set but I've never seen any lag.
It's thin, light and easier to hold weight wise than anybtablet I've ever used.
Browsing is great, movies look good and Sony have announced it will be supported through Android 4.4.
I have the LTE version and have found mobile signal and WiFi signal to be as strong as my other devices. I can stream movies from my bedroom over WiFi which has been a problem for other devices as the router is at the opposite corner of the house.
Sony's software is pretty none intrusive. You don't notice it as much as Sense or TouchWiz.
Negatives, not many. The ports can be a bit of a fiddle but they are not used too often and waterproofing may be a bigger bonus to you. Build quality is generally good and the tablet looks great but I can get a slight creak out of the back occasionally and also the back is a major finger print magnet.
I love this tablet and will probably keep it for at least a year - which is good for me!
Go buy one!
Previous Phones: HTC Google G1, HTC Hero, Nexus One, Nexus S, HTC Desire HD, Samsung Galaxy SII, HTC Sensation, Galaxy Nexus, HTC One X, Nexus 4, HTC One
Previous Tablets: Motorola Xoom, Nexus 7.
Current: Nexus 5, Sony Tablet Z LTE.