It changes the fight into a more 2D encounter, in which I spend more time looking over my shoulder than looking forwards. The AI will have a conflict of interest between diving to shoot me and avoiding the ground. Sometimes they get faaaar too carried away and lawn-dart into the ground in spectacular fashion - other times they pull up - depends on the sanity level of the pilot and situation etc.
In the long run, if it is just AI - you will get the odd oppurtunity to strike back at an AI's botched pass with a quick burst of fire. Other times, the flak will have a better target presented.
If it's players - it doesn't work as well - but if you are all out of options - there are worse things to do.
Note: Check where the radio mast is - it really ends your flight swiftly when you are watching behind you more than looking where you are going