[Adam]

Between 1 Jan and 31 May '44 the Luftwaffe launched about 4,426 bomber sorties and lost 243 of these (to enemy action). In addition, 227 Jabo sorties were launched (10 losses) while the RAF put up at least 4,400 night fighter sorties to counter these operations during the five months.

As to whether it was worth it or not - depends entirely upon which side you a referencing for an answer. For the Luftwaffe it killed civilians and military personal alike (satisfying Hitler's call for vengence), it disrupted to a degree the British production base and diverted a/c otherwise useful in offensive operations away from such operations. For England it was a minor inconvenience that did well to sap the already over-taxed kampfwaffe in the build up for Overlord and at the same time diverting units away from the Russian and southern theatre of operations.