I've used GDE since launch.
Had tried LauncherPro early on and switched out. Went back to LP for a week (until yesterday) but encountered multiple force closes, and the functionality for customizing icons was cumbersome.
In contrast, when running GDE I had forgotten what a FC looked like (can't recall having gotten a single one during all that time). The customization of any icon is simple long-press. I really like being able to add docks to the home screen itself instead of the bottom.
Zero lag, my Quadrant scores are identical with/without it running.
If you're looking for a trouble free launcher with all the trimmings (rotation enabled home screens, full customization, app docks, etc) you owe it to yourself to check it out.
FWIW, the most common complain is that it hasn't been updated since March. I consider that a pro, however, as during all that time I haven't encountered an issue needing a fix...