The developer behind this port has even gotten in touch with the guys at MIUI, and they seem to think that the port for the HTC Thunderbolt is good enough to be added to the list of officially supported devices. Now the only caveat here is that MMS functionality does not work, although with the option to send via email and other options such as Whatsapp, perhaps this may not be as big of an issue.
For HTC Thunderbolt owners looking forward to getting their hands on the ROM, head on down to RootzWiki for the download and full set of instructions, along with additional information about the ROM.