It's only really cheaper if you compare it to Intel's X25-E, which uses much more expensive SLC Flash. I suggest comparing it with the Intel X25-M instead. The Vertex does have a much higher write transfer rate, while the Intel drive seems to be better at random access and has higher IOPS.
A quick search brought up this review/comparison.
Personally I've been using a MemoRight GT (SLC) SSD for a couple of months, and later an Intel X25-M. I've also tried cheap MLC drives from G.Skill and SoliData X2. The latter is marketed as "Faster than Intel X25-M" at DVNation.com. Unfortunately it doesn't have a cache, so while transfer rates (both read and write) as well as random reads are very good, random writes are extremely slow (to give some numbers: 10'000 random writes of 4 KB each took 23 minutes (!) on the SoliData X2, compared to 30s on a Velociraptor or 1s it took on the X25-M). In practice this means the Intel drive beats it by a wide margin, even though some benchmarks might tell otherwise.
I'm aware the Vertex does have a cache, so this shouldn't be an issue. I'm just saying to take any hype with a grain of salt and wait for benchmarks that actually test the things you are interested in.
I posted a MemoRight GT SSD vs VelociRaptor article last year.
Haven't updated this with benchmarks of newer SSDs yet, but I've posted updated QuickBench scores.