They are an interesting technology but I would wait even on a high-end machine.

So far they are simply too small for most use.

The performance depends on what you are doing. In straight-up reading and especially writing the performance is bad. However, there's no seek time, no latency time--in most real-world situations they considerably outperform HD's.

They also are much more shock resistant than an ordinary HD, there's no vibration and they draw less power (but HD power is tiny compared to processor power anyway.)