Though we haven't chosen an interim minister yet, our congregation is going to use the services of an interim minister while we go through our current pastoral transition. And I think this is a good thing, mostly.
I think of two situations that illustrate the pitfalls inherent in calling a pastor without a time of interim:
1. A beloved pastor leaves suddenly for a new call. The congregation is heartbroken, and angry and confused, and maybe feels betrayed. There is perhaps a knee-jerk reaction that the church needs to get someone just like the pastor who has left, to replicate the experience which they thought was so good for them. It's not difficult to imagine the problems this could cause, as no two pastors have exactly the same gifts. As well, the church which loved the pastor may not have dealt with their feelings of anger and betrayal, and might take them out on the new pastor.
2. A pastor leaves a pastor call where there has been conflict and dis-ease, or where the congregation is foundering. A knee-jerk reaction on the part of at least some of the congregation might be for the next pastor to be the EXACT OPPOSITE of the one they just had. If the congregation has a little more time to think about it, they might realize that this wouldn't be the best idea.
A good interim period forces the congregation to wrestle with the mission God has given them, to consider their own leadership, and not just the leadership of the pastor. Effective ministry requres a partnership between clergy and lay leadership, and an understanding of the uniqueness each.
HOWEVER, I recently read this post over at the blog 8th Day Planner, and am pondering that there may also be pitfalls in interim ministry.
It seems to me that congregations in interim might get the mistaken impression that there is a Holy Grail of Pastoral Leadership, That Perfect Pastor for them. Also, a period of interim might be mis-interpreted as a period of internal reflection, and give the mistaken impression that a congregation needs to have Everything Worked Out Internally before they can turn outward to their community and the wider world.
But a healthy congregation is one that is doing what God calls it to do: loving their neighbors, doing good in their community, doing justice, loving kindness. You can't get healthy and then reach out. If you are a congregation, you get healthy (at least in part) BY reaching out.