iAPPs or not

For standard deployments of certain apps (e.g. SharePoint) an iApp can be a good solution. However, if you need more than basic customization of the VIP/pool config/monitors etc. it may be best to configure it yourself.

iApps still have some quirks and shortcomings. For instance, you will find that the system will mark all iApps as having been updated (and thus need their template re-applied) if you apply a HF to the BIG-IP. Another example is the basic HTTP-iApp, which is limited to assigning a single health monitor (vs. multiple).

iApps definitely have their place, but you will want to be aware of the limitations.