Why do people turn to (virtual) software appliances? I think the number one reason is ease of installation. If an appliance has one benefit, then it is that the system was put together by someone who really knows what he does. So the end-user can simply "plug it in" into the local network, do a few configuration steps and enjoy the software.
While we worked on the virtual syslog appliance, we have checked out various other appliances. They live up to this promise in very different ways. Some are really plug and play, while others are more a demo-type of a complicated system, where the user does not know what to do with the appliance unless he reads through a big manual. This is definitely not what people are after if they look for appliances.
With SyslogAppliance, I try hard to do things as simple as possible. I learned that I probably need to add some nice HTML start page, not only the plain phplogcon log analysis display. So I have now begun to do this appliance home page, just to see that displaying information is probably not sufficient.
I will need to do some basic configuration of the appliance, too. I was (and am) tempted to use something like webmin. But on the other hand, there are so many settings. I think most appliance user will never want to touch them. So a full config front-end is probably good for those in the know. But for the rest, a software appliance should come with the bare minimum of config options that are absolutely essential to do the job. For me, the "make everything configurable expert", this is a hard lesson to learn. Usability is top priority with appliances and usability means to present only those options that are useful to most folks (the rest will probably not use an appliance, at least not for anything but demo).
I thought I share this interesting thought on my way to creating great virtual software appliances. Besides logging, I have some other ideas (and all benefit from a great logging interface), but it is too early to talk about these, now.