I sometimes wonder if NVidia's GeForce-family isn't parralleling or matching the ATI problems. Most of the GeForce users out there go through initial growing pains, especially the motherboard issues of setting up 4X mode in a majority of motherboards out there.
NVidia is more likely to be run on BETA drivers because of some improvement or another, meaning that they are no different than using BETA ATI drivers. (The drivers releases for NVidia cards come three to four times more frequently, though.)
The DVD playback is anything but smooth on any GeForce family card using PC's below 1 GHz. I've seen P2-400's run smooth playback with a $60 Radeon VE!
NVidia doesn't demand quality 2D (RAMDACs) out of their generic business partners, meaning you have a good chance of poor image quality. NVidia cards in general tend to have a seriously dark picture, requiring a major shift in the gamma settings in every game. ATI cards tend to be bright in their games, requiring a shift to the darker side of the gamma settings.
NVidia cards often do not support 3V AGP boards, causing severe damage to both card and motherboard in those situations. I know, the same is true with 3DfX cards and 1.5V AGP boards...
NVidia cards run with compressed textures by default, causing the famous torn sky in Quake!!!. ATI cards have momentary whitescreens due to some driver problem. The NVidia problem persisted for several generations of driver releases until they finally found a physical problem in the NVidia chipset, right? 😉
NVidia has awesome framerate in their games, especially in the lower resolutions and 16-bit color. The lower the resolution the way better the performance; low end NVidia cards can run awesome framerates with 640x480 settings. ATI Radeons 7000/7200 (64-bit DDR, SDR models) in the low end tend to run optimal at 800x600 regardless if 16-bit or 32-bit color is used.
As far as the R300 goes, it'll probably be far short of expectations. ATI and NVidia always trump up the numbers and then release a disappointment.