The Corsair Blog has been publishing several really interesting articles, lately. In January, they wrote an editorial which quantifies the benefits of modestly overclocking CPU, GPU, RAM, and all of the above. Their benchmarks showed which tests favored what type of component.
This time, they look at the benefits of SSDs. Their Neutron Series GTX 240GB SSD was compared against a 3TB WD Black HDD (which is decent drive). To get into the campaign, they measured an SSD requiring a little over two minutes while the HDD took a little over two-and-a-half minutes. Multiplayer was much more significant: an SSD made it in game in 42 seconds while the hard drive took 69 second. That is a whole 40% faster.
Most importantly, getting into the game a whole 27 seconds earlier gives you first pick at vehicles. The game keeps them briefly locked to allow users to connect but, as is usual for Battlefield games, there is still an advantage for people with fast hard drives. Battlefield 2 was the unspoken benefit of purchasing a Western Digital 10,000 RPM Raptor drive, way back in 2006. You joined in as soon as you loaded which could mean nearly half of a minute to get your vehicle and go.
Shhh. Don't tell anyone.