There has been a shift in purpose for Lion Server. In Snow Leopard Server the philosophy seemed to be that all the easy stuff was fairly easy, but there was a steep learning curve for anyone who had never managed a server before. The medium stuff was mostly exposed in a GUI and so relatively easy, admittedly ambiguous at times, but you quickly ran up against a wall when trying to do interesting hard stuff so you had to drop down to Terminal. That was ok, however, as in theory anyone who wanted to do advanced stuff should be able to use the terminal anyway.
Lion is different. The easy stuff is brain-dead easy. Most services apple provides have an on/off simplicity to them that should make even the most beginner server admin stop and think “was that it?!”. My favourite change is the removal of the push notification server. Instead our servers can now hook up to Apple’s push notification servers and deliver notifications through them. Its as simple as clicking a button and we already know it works.
This is all made possible removing a lot of complexity from the Server App, which has more of a spiritual similarity to Server Preferences than Server Admin. The simplicity means a lot of features and settings are no longer GUI accessible, and Server Admin has lost the ability to configure things like web and calendar so medium and hard users now both have to use the Terminal to work OS X server.
This strategy is no more apparent than in the /etc/apache2 configuration directory, where Apple has written a comprehensive readme to start the intrepid new server admin off on the right track. It lays out what each file and directory is for and what files you can modify without interfering with Server App’s inclination for vomiting configuration over everything. They have engineered a clear point to insert your own apache configurations and hook them onto certain virtual hosts, and even have them depend on certain launchd system services.
Even though they have spent a lot of effort on improving the Terminal based administration its absolutely dreadful in comparison to a good Linux Server distribution. Most linux servers are designed to be set up on the command line and have standard tools that, if not easy, can be googled with great results. Whether Lion Server gets this same kind of attention remains to be seen. Going on web support for Snow Leopard Server config and issues I imagine support will be sparse.
So why run Lion Server? Why not. It hardly costs anything and you can run it on any computer. With it you get a great backup server for your other macs, you get iCloud features on your own machine with push notifications so you remain in control of your data (for better or for worse). The wiki server is cool and now tonnes better than before and I still believe Lion server is the best tool for managing suites of Macs and network user accounts (we still have Work Group Manager after all).
I guess that means OS X Lion Server has a place wherever you need an easy server for using with a bunch of Macs.