The S3 Pro's viewfinder (which appears identical to the S2 Pro) has a rubber eyepiece cup (which can be removed for accessory attachment). The view itself is good enough but as commented on by others has a simple cropped focusing screen which can appear small (especially when compared to the Nikon D70 or the Pentax *ist D). The S3 Pro has a sliding dioptre lever tucked away on the right hand side.
Through the viewfinder you'll see the center-weighted metering circle and five indicated AF area markers. Note that the active focus area darkens when selected. The on-demand grid lines can be turned on via custom function 2, these are useful for ensuring alignment when taking landscape or architectural shots. Along the bottom of the viewfinder view you will see the status bar. This provides you with an overview of camera (photographic) settings as well as exposure settings.
The S3 Pro's storage compartment is in the same location, bottom right of the camera rear. The door opens downwards and reveals both xD-Picture Card and CF Type I/II slots. I complained in my S2 Pro review that the compartment door on that camera had no rubber seals (and hence was potentially at risk from the elements, well the S3 Pro's door is no better.
On the left side of the camera (from the rear) are five of the camera's connectors; USB 2.0 (Hi Speed), IEEE 1394 (Firewire), remote terminal, DC-IN and A/V out. On the front of the camera there's a PC Sync terminal. Kudos to Fujifilm for including both USB 2.0 and Firewire.
The S3 Pro's pop-up flash (identical to the S2 Pro) is released by pressing a small button on the left side just below the flash. Opening the flash automatically enables it and charges the flash capacitor ready to shoot. The flash has a guide number of 12/39 (m/ft) at ISO 100 and a maximum sync speed of 1/180 sec. The camera uses the AF assist lamp for red-eye reduction.
The S3 Pro has a standard Nikon hot-shoe which can accept a wide range of Nikon Speedlights. It also now has full D-TTL flash sync support.
(No detailed specifications yet - more detail on this as it arrives)