Body elements

The FZ50 is powered by the same (7.2v, 710mAh) Lithium Ion pack as it's predecessor. The battery sits inside the grip under a sturdy spring-hinged cover. Thanks to the power-saving Venus III engine and lower resolution screen the already impressive battery life has been improved - by almost a third to approx 360 shots per charge (CIPA standard testing).
Above the battery compartment, on the side of the grip, is a sprung 'click in, click out' SD/MMC card slot.
The FZ50's ports are grouped together under a small, sprung cover on the left of the camera (viewed from the rear). Here you'll find a mini USB port, which also doubles as an AV out port using the supplied cable and the DC-in socket (for the optional AC adaptor). There's also a socket for the optional DMW-RS1 remote control.
The pop-up flash is activated manually by a small switch on its left side (viewed from the rear). It is fairly high - around 1.5 inches from the top of the lens barrel, which should help minimize red-eye, and fairly powerful. With auto ISO you can use the flash from around 30cm to 7m, and it recycles very quickly. All the usual flash options (on, off, red-eye reduction, slow synch) are available; the red-eye reduction system is a simple single pre-flash (around 0.8 seconds before the main exposure).
One fairly significant upgrade is that the FZ50 now supports fully dedicated TTL flash. The FZ30 was one of the only cameras in its class to offer a flash hot shoe, and the new model ups the ante (presumably thanks to the development of the L1 DLSR). There are currently two fully dedicated flash units available (though you can, of course, still use a less expensive non-dedicated unit).
Surprisingly the FZ50's screen represents a step backwards in resolution (dropping from 230,000 to 207,000 pixels). That said, you wouldn't really notice; it's still bright, clear and fast moving. It also seems very slightly better in low light, though in very bright direct sunlight it's as difficult to see as any other screen. New for the FZ50 is a 'FUNCTION' button, which brings up a quick 'mini menu' offering access to ISO, white balance, metering and quality settings.
A major enhancement introduced with the FZ30 is the added versatility offered by the inclusion of a 'tilt and swivel' mechanism. The screen is hinged at the bottom and can rotate through 180 degrees when folded out. The hinge has been redesigned so it now flips down through 180 degrees too, meaning you can face it forward for self-portraits. A small but useful improvement over the FZ30.
The electronic viewfinder (EVF) is identical to the one on the FZ30, and - of its type - it's very good. The 230,000 pixel resolution and sharp optics make it very usable, and the new larger eyecup is slightly better at keeping extraneous light out. I found myself using the EVF on the FZ50 far more than I ever do with competitor products (Sony H5, Canon S3 IS etc). It's no replacement for a bright SLR viewfinder, but it's not bad at all.
One of the biggest selling points of the FZ series is that huge Leica 12x optical zoom. The lens on the FZ50 appears to be identical to the one on the FZ30, which is no bad thing as it has proved itself to be an excellent performer. This lens is perhaps the biggest single reason the FZ50 can compete with entry-level digital SLRs; to cover its 35-420mm F2.8-3.7 range (with optical stabilization) using interchangeable lenses would be hugely expensive and very, very bulky.
Once you've used a 'super zoom' camera with a proper, damped, zoom mechanism it can be painful going back to buttons. The FZ50's mechanism is, again, a joy to use; smooth, fast and accurate, and is complemented by a 'focus by wire' damped manual focus ring.
On the side of the lens barrel is a large focus mode selector (Auto, AF Macro and Manual) . There's also a 'FOCUS' button - press this in manual focus mode to quickly activate the AF.
Panasonic supplies a 'flower' lens hood for use with the FZ50, which attaches directly to the lens barrel. The hood reduces flare in bright light - especially at the wide end of the zoom. You can't leave it attached permanently, however, as it can interfere with the AF illuminator in low light, and block the flash at short subject distances.
In a nod to SLR design the FZ30 has front and rear control dials for direct access to, amongst other things, shutter speed and aperture. One new - and very useful - change is that either front or rear dial can be configured to give instant access to AE compensation (just turn the dial and the menu appears).
The four-way controller has also changed (because of the FUNCTION button); there is now a small button in the middle (which basically does what the menu button on the FZ30 used to do). The functions associated with each directional button are now screen printed onto them.
The main mode dial has been redesigned slightly, the biggest change being a new 'CUSTOM' mode (which replaces one of the SCN positions on the FZ30). Up to three custom sets can be defined. Just about any camera setting at all (from exposure mode to ISO, white balance, focus and metering to basic camera settings like display format) can be saved in a custom set, making the FZ50 a powerfully customizable tool.