When you attach two displays or use higher resolutions, the remaining bandwidth for other devices is even lower, leaving only a small spark of the once mighty Thunderbolt. that it won't be able to drive any DisplayPort display.In a way, optical Thunderbolt with 100Gbps of bandwidth was a step in the right direction, but Intel postponed the optical route until some time in the future.
The problem with Thunderbolt is, that it's yet another proprietary interface. Admittedly for display connectivity - it is backwards compatible with DisplayPort 1.2, though only the Mini version currently used by Apple. Any other type of device either needs a replacement or an adapter to use it. even if you have financial resources for new add-on devices or plan to buy new ones anyway, these might not be compatible with your old computer anymore.
There is one more gripe Thunderbolt or shall I say Light Peak caused me. While this is not officially confirmed, it's evident that Intel delayed the introduction of USB in order to weaken the competition for Thunderbolt. As a major member of the USB Implementers Forum, and co-founder of the standard - Intel has a lot of influence on its development. While they didn't cripple the standard, they simply didn't add support for it in their chipsets and made hell to other companies that wanted to implement USB.inside theirs. The first Intel chipset adding USBsupport will only launch in 2012.