Win4Lin is not free software, nor is its code freely available. For some users, this can be a problem in terms of functionality and ethos. Further, the Win4Lin installation procedure still needs work. It relies on either RPM or the Debian package manager, although many people prefer tar' and gunzip'. Moreover, it insists on using a specific boot-script directory structure (the same used under RedHat and Debian). If this structure is not in place, the installation fails.
The installation also requires the patching and rebuilding of a kernel, which can be an annoyance to users who do not want their machines rebooted. Regardless, if it increases the functionality of Linux in such dramatic ways, and users require that kind of functionality, it is well worth it.
Some programs will not work with Win4Lin, specifically those requiring low-level file system access. Linux runs a very different file system to Windows, although running the VFAT file system under Linux can solve this problem. Programs that require direct hardware access - such as modem diallers or sound recorders/players - also will not function, as Win4Lin does not allow direct hardware access. On the positive side, this will prevent crashes due to poorly written programs. Finally, programs that need to use network protocols other than TCP/IP will not work.
Unfortunately, Win4Lin will not run Windows 2000. Given W2K's recent release, this is understandable. Future versions may support the new operating system. Regardless, Win4Lin is clearly a very good program that finally lets users have the best of both worlds. The commercial version sells for $US300; the student' release is only $US90 (but cannot be used commercially). See www.trelos.com for details.