Compared to most other contemporary digital SLRs the Sigma AD15 is distinctly short on features. While most of its rivals offer HD video recording, often with stereo audio, the SD15 has no video recording mode at all, neither does it have live monitor view. It has no image stabilisation system, although some Sigma lenses do feature optical stabilisation. It also lacks a sensor self-cleaning mechanism, but at least in this case it doesn't really need one. One unique feature of the Sigma body design is a sealed glass cover just inside the lens mount, protecting the sensor and mirror from dust.
The SD15 is also less well equipped in terms of creative photographic options than many of its market rivals. Most other DSLR cameras have a range of customisable pre-sets that can be set up for quick and easy use. The only image tone control available for the SD15 is a single menu option to adjust saturation, contrast and sharpness. It also only offers a maximum ISO setting of 1600, and that with very poor image quality. Several recent DSLRs offer three times this sensitivity. It could be argued that the reason the SD15 seems so limited is that it is primarily designed to be used in Raw mode, and that the custom functions that many cameras apply when shooting can be applied in post-processing, but this doesn't excuse the absence of useful modern features like video recording or live view.
The SD15 does at least have the basic necessary features for DSLR photography. It has a decent exposure metering system, with 77 segment evaluative metering, as well as spot and centre weighted metering, and the range of shutter speeds is on a par with most other DSLRs, 30 seconds to 1/4000th of a second. It also has other common features such as auto exposure bracketing, mirror-up mode, two and ten second self-timer, and it is also one of the few DSLRs on the market with an X-sync socket for use with a studio flash.