Nikon's D1 was a milestone in digital photography. Not only did it cost half as much as the cheapest Kodak option, but it marked the first time a single company designed both the body and imaging components of a digital single lens reflex camera. Canon's D30 is no less momentous, but to see why involves a deeper look at the technical details of the imaging system.
Canon does not intend the D30 as a direct competitor to the Nikon D1. The former lacks the sturdy feel and environmental seals of the latter, along with hits high-speed shutter and continuous drive. At $3,000 it's price closer to the Nikon-bodied FujiFilm Finepix S1 Pro, with which it also closer resembles in ergonomics and size. The D30 is slightly smaller than the S1 Pro, likely owing to the fact that it is a dedicated digital body rather than a modified film camera. Both bodies lack an integrated vertical grip present in the D1 but have an in-built pop-up flash.
As we just mentioned, the Canon D30 is the first entirely-digital designed camera. It is Canon's first home-produced DSLR. Unlike the Nikon D1, which uses a Sony-produced CCD, Canon has designed and fabricated their own sensor as well. The D30's is slightly smaller physically than the those found in the D1 and S1 Pro, instead opting for the same size as the earlier Kodak collaborations (1.6x focal multiplier rather than 1.5x). The D30 packs 3.1MP compared to the 2.6MP of the D1 capturing 12-bits per channel at either ISO-equivalents of 100, 200, 400, 800 or 1600 [although reviews seem to indicate there is no benefit to dropping from ISO 200 to ISO 100]. The most interesting aspect of the sensor is neither its size nor sensitivity per se, but that Canon has decided—and been able—to use a CMOS sensor rather than a standard CCD based sensor. Up until now, CMOS sensors have been unable to find a home in production digital SLRs because they have been unable to handle higher sensitivities with adequately low noise. The ability to overcome this limitation brings with it benefits both in fabrication (lower costs), and in the final product. CCD-based systems require more energy than CMOS-based systems, and the decision to use custom lithium-ion batteries gives a quite good 540-shots per charge according to Canon. An optional vertical grip ($200) also supports a second battery meaning that sacrificing a little portability could give you over a thousand shots without swapping batteries.
The Canon D30 has some drawbacks. It takes a few seconds to turn on or even awake from sleep mode. It is also limited to three auto-focus points which sports or wildlife photographers will find disappointing when compared to the 45-points found in Canon's top-of-the-line film cameras. It lacks an orientation sensor, meaning you will need to manually rotate images, but you can shoot straight to JPEG or as a 36-bit Canon raw file. The D30's 3 frames-per second (up to 8) is lower than that of the Kodak DCS 520/Canon EOS D2000, and its resolution in controlled studio environments will tend to fall behind the Kodak DCS 560 D6000. In just about every other measurable aspect, however, the Canon D30 signals that it is the best choice for Canon users looking to break into the digital world.