NOTE: I'll be reviewing the 4300 since it's what D-Link sent, but keep in mind that the 4100 can do everything the 4300 can, except for its wireless features.
The 4300 uses D-Link's standard plastic package, but is clothed in Goth black instead of the two-tone grey used by their other consumer products. It's surprisingly light and slightly longer, wider and taller than a VHS cassette. Although D-Link includes a stand so that you can stand it up on end, given its light weight you may want to just leave it lying down. There are two screw-head holes on the bottom in case you want to nail it down to your desk or mount it on a wall or ceiling.
The blue LEDs on the front panel are extremely bright (I was shocked at how much they lit up my office when I shut down for the night), but very tiny with also-tiny white-on-mirrored silver labels that I found difficult to read. You get a link / activity light for the WAN, each of four LAN ports and built-in wireless AP while a steady Power light rounds out the indicators. Note that there is no indication of link speed, either by separate LED or color change.
The rear panel contains the four 10/100/1000 LAN ports, 10/100 WAN port, power connector, Reset-to-Factory-Defaults switch, and RP-SMA antenna connector that sports a single screw-on 5dBi dipole antenna. Note that all ports (WAN and LAN) are auto MDI / MDI-X which means that they can be connected to most anything without worrying about tracking down a crossover cable. A nice touch is that the WAN port can have its speed forced to 10 or 100Mbps, but you can't set full or half-duplex mode.
The small power adapter is designed to take up only one outlet on all-blades-lined-up (vs. side-by-side) outlet strips, but only handles 100-120V AC input. Other stuff in the box includes a short CAT5 cable, "mounting kit" that includes wall anchors and screws and little plastic pieces used for locking together other stacked D-Link boxes, printed Quick Install Guide poster and CD with PDF User Manual and Tribes Vengence and Gamefly Video Rental trials.