There seems to be a lot of power attributed to the Elder Wand by various sources in Deathly Hallows.
However, looking at it soberly, there doesn't seem to be almost any actual evidence to support it. Of the known DH owners who used it to duel:
While wielding the Deathstick, lost a duel to Albus Dumbledore.
Dumbledore himself had evaluated that he was merely "a shade more skilful" than Grindelwald; which means, had the Elder Wand actually been "Immensely powerful, dangerous in the wrong hands" as Ollivander said, that should have easily nullified the skill difference.
During the duel at the Ministry, seems to have been equally matched with Voldemort. Again, Deathstick should have given him a pretty big edge.
Is the fabled power of the Elder Wand just that, a fable as far as dueling is concerned? (I know that it was able to repair Harry's original wand which does make it unusual/special, but that was NOT a duel situation - I only care about duels, not boring work tasks).
Just to clarify: an equivalent real world situation would be the Spear of Destiny. It's fabled to make the owner an unbeatable military commander. It was reputed to have been owned by both Napoleon and Hitler during their military expansion. However, those 2 facts obviously do NOT constitute proof that Spear of Destiny does have the attributed power - even if it exists and they both owned it, it would have been merely correllation, not causation.
Same way, just because the tales and fables in Harry Potter Universe claim that some warlocks were made unbeatable because they owned a special wand, it could easily have been simply because they were unusually powerful wizards, ala Voldemort, and NOT due to some special wand powers.