I've been living in Germany for some time now and most people I know who were alive in the 40s have told me about how people rushed to the West in order to avoid the Russians in the tail end of the war. The Americans in particular had a good reputation for taking care of German civilians and POWs.
Recently however, I've seen reports that "hundreds of thousands" of women were raped by Americans during the invasion (including through allied countries) and during the occupation of Western Germany.
EDIT TO ADD SPECIFICS ABOUT "REPORTS"
And also the Wikipedia entry on Allied war crimes in WWII
http://en.wikipedia.org/wiki/Allied_war_crimes_during_World_War_II
What is the consensus under historians?
I'm going to tackle your question in two parts. The first part, I'll go into the types of war crimes that were carried out by Western Allies (I'm assuming from your question, that's chiefly what you're interested in, but if you're seeking an answer inclusive of war crimes committed by the Soviets, I can tackle that later). The second part I'll address the Telegraph article discussing the professor who speculates that there were hundreds of thousands of rapes.
Now, in regards to war crimes committed by the Western Allies, they did happen. As much as I've seen some people pretend that some of the actions committed by western troops weren't really war crimes when compared to the actions taken by the Germans or Soviets, it doesn't change what those actions were. The majority of war crimes attributable to Western Allies (particularly the Americans and British) are incidents usually surrounding summary executions of prisoners of war shortly after their capture. These kinds of incidents usually occurred in the aftermath of a traumatic or catastrophic event (usually after a particularly intense firefight or battle where high losses may have occurred) for the offending unit. One example, is a written order that was issued shortly after the start of the German offensive in the Ardennes in December 1944, that stated no SS or German Paratroopers were to be taken prisoner and should be shot upon capture. Another example is the reprisals carried out by American GIs at the liberation of Dachau. Numbers between 30 and 500 are given by various sources for the number of guards and SS personal executed shortly after the camps capture by American forces.
Both of these actions fall under the definition of a war crime. Primarily due to the fact that regardless of how reprehensible or terrible the actions of the captured guards or soldiers were towards the prisoners in Dachau or others, the articles of war that American forces were operating under called for these guards or soldiers to be detained so that they could later be tried for any crimes they committed, not summarily executed upon being captured.
Other examples include summary executions of captured soldiers shortly after fighting had taken place. This was something that more commonly happened during major operations, like the Normandy invasions, and the Battle of the Bulge.
There are a small number of incidents recorded of civilians being purposefully killed by Western troops. There is particularly one known as the Canicatti massacre, in which eight (estimated) Italian civilians were killed in an attempt to disperse a crowd that was looting a recently liberated town. Other smaller scale incidents did occur in the North African theater as well as Western Europe, but nothing so large in comparison to Soviet or German war crimes.
Now, as far as the Telegraph article and Professor Gerhardt's claim that there were "hundreds of thousands of rapes of German woman", at the hands of both American, as well as Soviet soldiers, this is where it gets tricky.
There were certainly rapes that occurred both within the American and Soviet zones of occupation (as well as during the invasion of Germany) by their respective forces. As far as that number being in the hundreds of thousands, that is possibly true for the Soviets, but not for the Americans and other Western Allies. For the Western Allies, particularly the Americans, the generally agreed upon estimate for the number of rapes committed by those forces is somewhere between 11-14,000.
If you read in in the article, you'll notice that Antony Beevor chimes in to say that even he finds those estimates given by Prof. Gerhardt to be quite high (in regards to the Americans number) and very likely incorrect, primarily due to both her methodology as well as her source for that number, the records or diaries of Bavarian priests. Those records are great primary sources by the way, but not necessarily the most reliable or accurate sources if you want to establish the number of rapes that occurred. An important thing to remember here is that one must compare multiple primary sources to make a solid claim like the one she is making here, otherwise your data/claim is too susceptible to bias or inaccuracy.
Beevor, has written extensively on the Eastern Front and the subsequent Soviet occupation of Germany. His own estimates, state the the number of rapes that occurred under the Soviet occupation is somewhere around 1.4 million (which seems high but keep in mind, this is over a multi-year period where a very large number of Soviet troops were in Germany and other Baltic states). Beevor's sources ranged from NKVD reports to documentation on the number of abortions that were carried out by German woman in the immediate aftermath of the Soviet invasion and occupation.
So in summary, there were certainly a high number of rapes in Germany that were carried out by Allied soldiers, but the overwhelming majority of those rapes were carried out by Soviet soldiers, who were often encouraged and rarely disciplined for those rapes. Where the Western Allies certainly did have rapes occur under their watch, though the numbers were far far lower, and more often than not, the offending parties when caught, faced prosecution.
Sources:
An Army At Dawn by Rick Atkinson
For an interesting perspective on the Dachau reprisals committed by the American Thunderbird division, I recommend the Liberator. This book is focused on Felix Sparks, an American military officer who fought in Sicily, the Vosges, and helped liberate Dachau. He was in command of the men who fired on the camp guards at Dachau but later absolved of any complicity (he was in another area of the camp at that time, as the liberation of a concentration camp was beyond the ken of almost any American officer then). Sparks's remorse is interesting, given that he had just seen the horrors these camp guards presided over.
However, avoid this book. Authored by a battalion doctor, Howard Buechner, the text claims that 520 men were killed in the massacre, with 346 being machine-gunned by a then-dead at the time of publication comrade of Buechner's. The actual number was far less. Moreover, under oath in 1945, directly after the massacre, Buechner claimed he refused to treat wounded SS at the camp and personally saw 15 men dead along the wall where the shooting occurred.
His latter-day claims are rebutted by pretty much every official source, including recently declassified internal Army review documents.
Nevertheless, a black mark on the American Army's conduct in that war.