I have both the FZ150 and the FZ200. The FZ150 was a very good camera, the FZ200 is better in several areas. The recently posted FZ200 review is very fair to the FZ200 and I recommend reading through the Verdict section as it tells the story well.
However, I will add that the camera can be improved by fiddling with the settings. There has been a lot of testing and posting on the FZ200 over on the DPReview forum over the optimum settings for shooting JPEGs. My personal conclusion is that leaving the image type at "standard" and leaving the sharpening, contrast and noise reduction at their center positions (the factory default) is best; but then turning on iResolution to gain a little additional sharpness, detail, and some smoothing in solid color areas, like sky.
I'd also recommend setting the upper limit for Auto ISO at 800. ISO 1600 is usable; but not quite as good as 800 and with the constant f/2.8 lens, you'll seldom need to go higher than 800.
The new EVF is amazing.
Also, the control layout and options are much improved over the FZ150, and the grip is a little fuller and a little taller, and feels better in the hand. This is a camera you can quickly fall in love with.
One important comment. On some cameras, the detents that hold the hood in place are VERY stiff.
If yours is one of the very stiff ones, be very careful not to mount or dismount the hood with the lens extended as you can damage the lens.
I filed down the locking lugs on mine to reduce the force needed. The FZ200, like the FZ150 is one of the few superzooms that can use both filters and the hood simultaneously.