Ryan,
personaly I am a DNN User since 2003 and see issues on Upgrades on the early time. But since DNN 4 It Comes more and more stabillity. Now I would say it is a stability System.
I have never used the web installer to install . And have for years no real error in the update and installations of the base system packages found . Most errors in leigen additional extensions installed on the Windows system , or in the configuration .
In terms of installing the base system , there are a lot of problems that can aufteten in relation to the respective system. These are no configuration errors could dotnetnuke part , but have to do with the deployment of the respective Windows systemes and any installed extensions . FOR EXAMPLE I know from personal experience that there are significant problems with the WIF (Windows Identity Framework). Other extensions have already caused problems here .
Generally requires DNN7.1.x at least one Windows Server 2008 SP2 and SQL Server 2008 or higher. Furthermore, the NET Framework . 4.0 or 4.5 is required. The application pool should be configured in integrated mode and disabled 32 bit mode . The Application Pool Needs write and change rights . Then the IUsers (annnonymous user) should have read permissions.
There also some SQL Server Tasks that is needed after install them. So the protocols for Client and Server must be configured.
We have a lot article and Videos on this page, that descipt the install on details. Have you ever installed a SharePoint farm? I think not. In this comparison, the Installation of DNN Platform is a child's Play.
On your post I miss details of your issue you have on the install, so I can not go into it to try to reproduce it. So clear description of your issues will be helpfull.