Thunderbolt has been out for over a year, but there’s still a disappointing lack of peripherals. The few that are available are very expensive, and many potentially useful ones — such as Gigabit Ethernet or Firewire 800 adapters — don’t exist yet as standalone peripherals. (You can get a Thunderbolt-to-Gigabit-and-FW800 adapter for $1000 with a free Apple Cinema Display attached.)
I would call Thunderbolt a disappointment so far. And I wholeheartedly agree that USB 3 will become the standard, it’s just a matter of when Thunderbolt will die off, not if.