620,000–950,000 casualties
8,000 aircraft destroyed
6,200 guns, 2,500 tanks, and 70,000 trucks destroyed or captured
source: http://en.wikipedia.org/wiki/North_African_Campaign
Also, the fighting in North Africa did much to teach the British and Americans about modern warfare. How well would they have fared in their invasion of Europe with their last fighting encounters with the Germans having been Dunkirk 1940 and Greece 1941 for the UK, and ZERO for the Americans...
It should have been in the Axis interest in 1940 to seal off the Med on both ends and keep out the Allied navies and armies.
That was not possible because
1) the Italians were a total disappointment
2) Rommel could not get to Suez because of insufficient supplies making the trip from Italy (ULTRA was an decisive factor)
3) the Allies won the Battle of the Atlantic (ULTRA again decisive), thereby ensuring their quantitative superiority in all theaters and in the air war
4) The Axis could not project power to Gibraltar/ Marocco
Hence, having destroyed the Panzerarmee Afrika, the Allies proceeded to invade Sicily and mainland Italy, in early 1944 tying down 55 German divisions in the Med TOO for their own 21, thereby providing relief to Stalin and Operation Overlord.
Unfortunate, but since Gibraltar and Suez could not have been held (even if taken), the Axis needed to place troops from Perpignan to Rhodes, conserve forces, and wait for the Allies' move.
Germany could and should yet have provided radar and day and night fighters als well as bombers to be based in Sicily, as happened in OTL in early 1941.
But, what if no Rommel, no DAK, and none of these German troops would have been sent to Africa in 1941 or later?
What would have happened with regards to
- German-Italian relations
- Italy holding onto Lybia
- Greece and Yugoslavia
- Allied shipping between Gibraltar and Suez (stopping it would be my minimalist objective; it is an important one)
- Italy being exposed to aerial bombing from Lybia
- Italian morale and Italy remaining in the Axis
- Timeline for the Allies landing in Southern Europe (where?)
- NOTE: the word "Malta" is forbidden in this thread

My opinion:
With hindsight, Germany should not have sent troops to Africa. These thousands of Axis tanks, guns, and vehicles and hundreds of thousands of lives killed and captured were wasted there. The Third Reich's empire in WW II was a continental one, and it should have been defended on the continent of Europe and the skies above it. The war against the Western Allies needed to be won in the Atlantic.