Weep
Cannot really see much advantage at the moment except the use of a Compact Flash (although the don't say which type the PDF file does indicate Microdrives can be used so this implies type II) which will allow more memory for storing the maps.
They do however only reference USB1.1 so any Apple users can forget it
There is no increase in the number of routes and waypoints so it looks like that is using the same internal memory store as the SPIII and therefore likely you will still have to download maps and routes seperately for speed.
The level of accuracy has improved. It is difficult to tell from the Spec sheet what changes have been applied to the firmware to improve. Although there is no change in the accuracy figures indicated.
The screen display has actually decreased 3.3x1.7 from SPIII 3.4x1.8
The weight has gone down from 635g to 420g
There seems two versions (2610 & 2650). Only the 2650 has "dead reckoning" which looks like it will remove that sudden loss of signal destroying your routing in city "canyons" just when you most need it. However the spec sheet implies that an extra capable is required to support "dead reckoning" so that may be difficult for motorcycle users!!!
They still use Mapsource so there is no change there in the cartography capability.
However the remote control will be really useful and all motorcycle riders should upgrade just for that capability!!!
But really the message should be for those who don't have an SPIII.... now you will be able to get one really cheaper...
Actually considering the time since the SPIII launch this does not seem a major breakthrough...