Samsung 840 series SSD drives are great.
Sustain ~520MB/Sec on reads... when connected to an Intel SATA-III controller.
If used as a boot drive, don't expect the OS to be three times faster than if installed on a conventional HD.
The OS is slightly faster. Apps open up quicker.
Where SSD truly shines is streaming large sample libraries.
They load faster... and you can stream massive amounts of polyphony.