Most of the times manufacturers advertise read/write peak speeds in MB/s. I am wondering that is it how relevant? What's the most important performance factor in an SSD when it comes to desktop use (Web browsing (loading data from cache), starting applications, using Photoshop, programming, office)?
Access time - how long it takes for the drive to find the data you're looking for. This is measured in milliseconds. Hard drives have access times of about 10ms or so, while SSDs are up to 100 times faster.
Transfer rate - how quickly data can be transferred once it's been found. Transfer rates are measured in MBytes/sec.
For booting and starting applications, access times are the most important factor. In disk benchmarks the best way to gauge access times is from the random I/O tests for relatively small I/O sizes (i.e., 4K random I/O rate).
I am not particularly fond of synthetic benchmarks. The most important factor for me is how well will an ssd performs when running my own mainstream professional applications (such as Adobe products) on my computer. Synthetic benchmarks only provide a rough approximation of what to expect.
When it comes to benchmarks the "got to have the biggest, fastest, baddest" syndrome seems to be in effect. Gamers and enthusiasts love numbers. The bigger the number, the better. Companies are more than happy to oblige. They're very creative at configuring hardware and benchmark applications to make their product look like the greatest thing since sliced bread.
A solid state drive will do absolutely nothing for web browsing. You are totally at the mercy of the world wide web and your Internet provider.
A solid state drive will definitely start programs faster than a hard disk drive. The big question is how does an ssd perform during typical use. The results will vary.