is the ssd much much faster than the 4200rpm option?
In many tasks, it will be quicker than the 10,000 RPM Raptor hard drives. At least if they use a good SSD, it will.
Check out TomsHardware or Anandtech's coverage of SSD drives and see how they compare. For most people, the difference will be really impressive. Especially people used to laptop hard drive speeds.
It will also pull 1/10th the battery power to do the same amount of work, and generate almost 0 watts of heat.
But for 1000 dollars, i don't think it is really a smart buy yet. Now in a couple of years, as early adopters buy these things at insanely high prices and hopefully encourage manufacturers to ramp up mass production, we'll see the price per GB drop off to something probably closer to double that of spinning hard drives, and at that point, you would be stupid not to buy one as your main boot/scratch drive. Rotating hard drives will continue to increase in storage and decrease in price for a long time, so they will probably still make sense for "mass" storage of things like audio, video, and pictures. Media storage, basically, and backup.
but yes, SSDs are, even at this early stage in their life cycle, easily faster than regular hard drives.