I covered the design details of the G2 in this Inside Story article, but, to recap, the design is based around the Broadcom BCM5354 802.11b/g Router System-on-Chip with BroadRange Technology, 8 MB of RAM and 2 MB of flash.
The circuit design is essentially the same as the most recent WRT54G boards (the WRT54GV8 and WRT54GV82). The key difference in the G2 is that it uses dual internal, fixed position, non-upgradeable antennas vs. the external, movable, upgradeable antennas found on the WRT54G.
The feature set of the G2 is essentially unchanged from that of the G.
Routing performance measured around 72 Mbps in the WAN to LAN and LAN to WAN tests. But when both directions were run simultaneously, average throughput for the 1 minute IxChariot run dropped to 45 Mbps, due to what appeared to be a battle for throughput between up and download that resulted in WAN to LAN traffic grinding to a virtual halt for most of the run.
This inability to handle full-speed traffic in both directions simultaneously caused a dismal performance in the Maximum Simultaneous Connections test of only 8 connections (4 up, 4 down).
Wireless performance was tested with the latest-generation WPC54G V3.1 card, which uses a Broadcom BCM4318 AirForce One Single-Chip 802.11g Transceiver. The router and card stayed connected during my open-air "walkaround" test in the difficult test Locations 4 and 5 with 1-2 Mbps throughput.
But the throughput vs. path loss tests run in the Azimuth tester showed slightly shorter range and a faster falloff in throughput than the WRT54GV5 and WPC54G V3 pair.
Updated 6/19/2008 - Read the full review.