It looks like HTC's unlocked bootloader policy may not be just what everyone was looking for, and several key portions of the firmware remain locked. What appears to be the case, is that using HTC's tool does unlock your bootloader, but doesn't grant you S-off status. Right off the bat -- if you don't understand what S-off means, you don't need it. It unlocks the ability to flash things like radios and hboot versions, which are all closed and protected files from HTC and the carriers.
What HTC's method does give you is the ability to flash a modified version of a custom recovery, which can be used to flash the files needed to root the phone. Once rooted, you can run root-required apps and have read/write permissions on the system files. As it stands now, if this is all you ever wanted to do anyway, HTC's tool will work for you. If you think you might one day decide to get a little deeper, I suggest you wait it out for a while. Will methods to flash ROMs get figured out for phones unlocked with HTC's tool? Probably. There's also a chance the boot partition is able to be flashed. The one thing we all know for sure is that HTC has made it very hard to go back if you go through with updating and using their unlock tool. Waiting to see how this all plays out is probably the wise decision.
There are also Internet rumors flying around saying HTC will send another update to give the phones S-Off status, or that this is just step one and they will release updated tools to do it. At this point, all that is just speculation. Personally, I'll wait and see exactly what works and what doesn't before I decide to buy another HTC phone. If all they have done is block access to carrier-protected files and still allow the flashing of a new system, data, and boot partitions, I can accept that position. If they have blocked the flashing of new kernels or the boot partition as a whole, that's another matter. With all the development going on for the Sensation and EVO 3D, we'll know soon enough.