I purchased the A300 back in May and I can't say enough about this camera. Some people have already pointed out in this thread but just as a repeat, Sony has been producing sensors for years for other DSLRs to include Nikon (not all but some).
I agree that Sony's kit lens may not be quite as good as Nikons, It will hold its own and I would say is comparable if not better than Canons and if you want to talk quality, you can't get much better than the Carl Zeiss lenses that are offered.
Other features that turned me on to the Sony were its ease of use for a novice as an entry DSLR, the live view function, and the tiltable screen. As for easy to use, you can set this up to work just like a point and shoot if so inclined only with much better pictures. The live view is nice sometimes and the way that Sony has it set up, it doesn't expose the sensor until you shoot the picture unlike all the other DSLRs with live view. Finally, as far as I know, the Sony is the only DSLR that has a multi-angle, tiltable screen for low and high angle shooting.
For the money, I think the A300 gives the best bang for the buck. The A350 is the same exact camera except with a higher megapixel rated sensor but IMO not needed unless you plan on blowing your prints up to poster size or larger so save your money and buy some extra lenses or an UW housing for it.
If you have any questions or would like to see some sample pics, feel free to pm me and I will help you out as much as I can.