I've been a satisfied user of the Coolpix 3100 for three years now and I just decided to upgrade to the P4. I've been way too busy to seriously explore the camera so I'm writing this review at quite an early stage - but so far I can say I'm very happy.

The main criteria for me on selecting a replacement for my old workhorse were:

It uses SD cards. I wanted to say goodbye to my collection of CF cards because my computer won't take them without an external reader and I want to get into SD cards so I can quickly transfer pictures to my PDA without the need for an intermediary device. (I'm actually using mini-SD cards in the camera.) I'd love it if this camera had bluetooth but at the time of writing this is simply not a common option among digital cameras.

I also wanted to say goodbye to my collection of AA batteries and charger. I was very attracted by the P4's tiny mobile-phone-style battery and convenient charger. I was surprised to hear when making the purchase that there are chargers available now which can charge two AA batteries in just a couple of hours but they're certainly bulky affairs - when you put them next to the tiny matchbox-sized recharger for the P4's neat little Lithium battery the thought of carrying one of those bricks around on an extended trip looks like an unappealing option.

Other attractive features are:

* 8 MegaPixels - this wasn't an overriding attraction for me; I find 3 MP is enough for my needs but I'm sure one day I'll appreciate the larger resolution when I'm taking more than just a bunch of snaps.
* Vibration reduction (VR) - So far I'm impressed with this. I'm an 'available light' kind of photographer and I've taken great shots indoors with the shutter speed at 1/8 sec using this feature.
* Large lens - the lens is a serious affair. The first few shots I've taken suggest it's even better than the already-impressive optics on the Coolpix 3100.
* Video with sound - the lack of sound was something which bugged me a little bit about my last camera but I seriously doubt I'll be making much use of this feature. Note however that the video offers multiple modes and I can say I'm very very impressed with the clarity of the results in low-light situations.
* Slimmer build - I do confess to being slightly ambivalent on this one. It's much easier to fit in the pocket than my old camera however I always worry I'm going to drop the thing... Something you have to get used to perhaps...
* Large screen - Very impressive. Lovely and clear with lots of information.
* Internal memory - it has 23MB of internal memory. This should allow you to store about 30 pictures without the need for a memory card. Most wouldn't care but I reckon this could really come in handy during some unforeseen occurrence (like the memory card being full/damaged/required elsewhere).
* Voice memo - it's possible to append a voice memo to a particular photo. Not something for everyone but I could imagine it coming in handy.
* Lastly the camera has highly configurable exposure modes and sophisticated metering and autofocus options - most of which I haven't tested yet.

Finally I should note the minor gripes I had with my old Coolpix 3100 and note how the P4 addresses these:

* On/off switch - my old camera had a clumsily-positioned switch that always got caught as I was putting it into the case. The P4 has a press-down affair which is much better.
* Flimsy cover on battery compartment - the plastic catches broke off more than once on the old camera and were a constant source of worry. The P4 has a much better design. Actually the P4 incorporates a lot of metal casing and parts, and in general it seems to be more sturdy.
* Lag - on my old camera there was a lag on metering, flash charging and focusing. It took a long time between switching on camera and it becoming ready to shoot. This is fixed to a large extent in the P4. The amount of time from switching on to shooting is as low as three seconds.
* The dial at the top - the 3100 would always come out of my pocket in a different mode to the one it was on when it went in. I'd say this has only been partially addressed on the P4. A shame.

Small gripe: I'd say the controls are less intuitive on the P4 than on my old 3100. However one must remember that there are many more options and functions at your fingertips with this camera. Another one: the tripod mount is positioned all the way off at one side. It's surely not an issue with the camera being so light but ... wouldn't it be better under the centre of the lens? I suppose one possible advantage with it as it is would be that you could change battery and/or memory card without unscrewing from the tripod.

Of course up to here I've taken for granted the superb image quality you should expect with a Nikon. So let me be clear ... with the P4 you're getting superb image quality. Right I've said it. It has surpassed my expectations ... which were already high.

And it's great value. It cost me US$280. I'm expecting to get some great results with this camera.