Thunderbolt (formerly known as Light Peak) offers high speed I/O on the new Apple MacBook Pro. Fast I/O (think super-fast storage) has been a long time in coming, and Thunderbolt eclipses anything previously possible on a laptop.
But all is not perfect, as there are some limitations in addition to the benefits.
The benefits of fast I/O cannot be underestimated— a MacBook Pro can now use an attached disk array as fast or faster as just about anything on a Mac Pro, and much faster than eSATA (assuming a fast enough device).
Coming in 2011 from various vendors, we can expect SATA 6G solid state drives capable of nearly 500MB/sec (4Gb/sec). In that context, even 10 Gbps already looks too slow, since 3 such SSDs would max-out the Thunderbolt bandwidth. Then again, 500MB/sec is faster than most everyone needs anyway.
Daisy-chaining and too few ports
Daisy-chaining means to connect devices in a chain; plug in the first device to the computer, the next device to the first device, etc.
Daisy chaining works, but is a hassle: suppose you want to connect one more device temporarily. Since the existing devices are running, and in a chain, the computer has to be shut down; one can’t unplug a working disk drive. Then when done, you must to reverse the process. This makes using Thunderbolt for card readers, temporary backup drives, etc not so convenient.
The solution is multiple Thunderbolt ports and perhaps this is what will occur on the Mac Pro and maybe even the iMac and future MacBook Pro models.
The display will suck up some bandwidth, and how much that will degrade demanding I/O requirements is not yet clear (think 3 SSDs each doing 4Gb/sec).
Since the Mini DisplayPort has been replaced by Thunderbolt, it’s not clear that DVI displays will necessarily work as before (with adapter). But perhaps they will.
Since Apple’s existing displays (and others) have only one Mini DisplayPort, one cannot plug in dual displays, since there would be no way to daisy-chain them.
Power over cable
Apparently 10 watts of power can be supplied. Which means one or perhaps two small devices, and little else. Good, but not great.