Like any waterproof compact worth its salt, the D20 feels like a sturdy camera. It's made almost entirely from plastic but build quality is good. We dropped our D20 a few times while out and about, and the casing shows no visible signs of damage. The camera handles fine but there's room for improvement—some kind of indentation or grip handle on the front would be a good place to start. Here, the smooth metal plate—which merely seems to be decorative—does nothing to help you keep hold of the D20, whether shooting underwater or snapping on dry land. That said, the D20 is supplied with a wrist strap with a handy toggle so you can firmly attach the camera to your wrist. Plus, you won't have to fiddle around trying to thread the end of the strap into one of those tiny holes, as it attaches to the camera body with a practically designed metal clip. When taking photos underwater, the bright blue buttons stand out from the black camera body well, which is a real help. However, placing the playback button on the top of the camera next to the shutter-release maybe wasn't such a great idea. Otherwise, Canon's graphic interface is nice and it's always good to see a separate video record button.
The LCD boasts 460,000-dot definition and, like almost all other waterproof compact screens, it's too shiny to be used comfortably in all situations. The onscreen image is fluid, but colour fidelity isn't great, with an average Delta E 94 of 9 (this should be 3 or less for accurate colours). Plus, bright, light areas are easily overexposed onscreen. Note that the D20 lets you flick through images in playback mode by tapping the screen, but it's hard to see how this is any more useful than just using the arrow buttons.
The D20's built-in GPS finds the positioning satellites quickly. The GPS can be used in two modes—one that disconnects the GPS each time you switch the camera off to help save battery life and another that registers the camera's position at regular intervals (even when switched off) to trace a full journey (the data can be recovered in a separate file).
Although battery life isn't amazing, we still managed around 200 shots per charge (with the GPS in standard mode and occasional use of the flash). That should be enough to get you through a day at the beach, at least.
Finally, it would have been nice to see a more secure-feeling locking system for the battery and connections compartments. Here, the catch is just a bit harder to open that the one seen in Canon's previous model.
The D20 is on the better side of average for a waterproof compact. It starts up quite quickly and the autofocus works well in good light. However, this compact soon starts to show its limits. In low light, focusing is much more temperamental (which is a shame, since light quickly gets scarce underwater). Plus, photo-to-photo turnaround when using the flash (which you may often need underwater) is a bit on the slow side, at 3.5 seconds. That's long enough to find yourself cursing the D20 when you miss that fish swimming by.
It's not like the 28-140 mm lens used in the D20 is a bad or anything, it's just that the one in Panasonic's FT4 does a better job, keeping quality more consistent over the frame at wide-angle settings. In the middle of the frame, the D20 lens is good, but the edges of shots are hazy. However, images get sharper and more consistent as you zoom. The D20 also has an excellent 1 cm macro mode. However, it'd have been nice to see some built-in LED macro lights like in the Pentax WG-2 to help brighten things up.
Even though the D20 has a BSI CMOS sensor, it doesn't handle digital noise quite as well as Panasonic's CCD-clad FT4. However, picture quality is still above average, with shots that are usable up to 800 ISO. We wouldn't recommend using the highest two ISO settings unless you really don't have a choice. Anyway, you can always try using the flash first, as exposure is pretty good.
The video mode is pretty standard stuff. Video is recorded in Full HD but the framerate is limited to 24 fps (frames per second), which sometimes means that movement doesn't look as smooth as it could. Surprisingly, though, the D20 has a 120 fps video mode in 640 x 480 pixels, which is ideal for slow-motion filming. Image quality is fine, with good exposure and few compression-induced artefacts. Sound is recorded in mono—there's only one mic on the front of the camera—but this is duplicated to render the video audio in stereo. Note that you can't take a photo while filming video but you can use the optical zoom, which is nice and quiet.