In its day, OS/2 struck a good balance between hi-tech features and reasonable performance on the hardware of the time. It was also the first consumer OS to ship with TCP/IP networking and an Internet dialler as standard.
The fact that it never quite broke through to the mainstream wasn't as much of a handicap as some might think as OS/2 had some high quality shareware, commercial and freeware native apps. OS/2 could also run a lot of software which had been created for other platforms or that had been created in a platform independent manner. For example, it was the first consumer OS to ship with Java support as standard; OS/2 had probably the most comprehensive DOS support of any GUI OS; it could run Win3.x software. In its later years, an impressive project called Odin enabled a OS/2 to run a surprising amount of 32 bit Windows software. In other words, you had access to almost any type of application, even if it wasn't a native OS/2 application.
However, the very features which made OS/2 the OS of choice for so many have faded in importance. It is with a heavy heart that many of OS/2 former users (myself included) have to admit that they don't really want to go back to OS/2 anymore than they would trade in their broadband Internet connection for dial-up ANSI BBS access and 320x200 VGA games with ad-lib music. Perhaps IBM could have kept OS/2 relevant but they didn't make any serious efforts to develop it beyond about 1996.
What features, for example, does the kernel offer that modern operating systems do not? For that matter, does anyone really want to use an OS that uses drive letters?
In conclusion, in my opinion, recreating OS/2 would be more work than starting an OS from scratch, considerably more work than improving another OS and ultimately, produce a less useful result than either.
The website includes a fairly comprehensive outline of what the developer would like to accomplish with this relatively new project. As the project is new, the bulk of materials are design docs as opposed to actual runnable code. Despite this wealth of design documentation, actual design specs are still rather conceptual rather than specific. For example:
The the kernel hasn't been settled upon yet. It might be based upon a Linux kernel.
The exact nature of GUI is still undecided. In design terms, it will not be based on X Windows but it will make some concessions towards the PM+WPS nature of OS/2. How API compatible it is, is also not specified.
Source and binary compatibility with OS/2 is still undecided.
It's impossible to make reliable judgements about the viability of a project which is still at the design stage. In its favour, at least the planning stage has been extensive. Also, it's worth noting that the people associated with the project have a track record for software development on OS/2.
OSFree was initiated in 2000 but as with Voyager, the project exists as a set of design outlines and some test code. It would seem that they have settled on the idea of using the L4 Micro-kernel and have successfully recreated some of the OS/2 CLI tools. The project certainly isn't dead though, there is some activity in the forum.