However, his advance panicked the allies and mostly cut them off from Calais, so he cost them a lot of materiel. To quote wikipedia:
"The BEF lost 68,000 soldiers (dead, wounded, missing, or captured) from 10 May until the surrender of France on 22 June. 3,500 British were killed and 13,053 wounded. All the heavy equipment had to be abandoned. Left behind in France were 2,472 guns, 20,000 motorcycles, and almost 65,000 other vehicles; also abandoned were 416,000 short tons (377,000 t) of stores, more than 75,000 short tons (68,000 t) of ammunition and 162,000 short tons (147,000 t) of fuel. Almost all of the 445 British tanks that had been sent to France with the BEF were abandoned."
However much Rommel actually cost the Germans, I suspect he cost the British rather more, so on the balance he was pretty successful.