Wiki:
"On February 19, 2007, the upper stage which failed to bring Arabsat 4A to its correct orbit exploded over Australia after almost a year in space, creating a cloud of space debris.[5]

On September 5, 2007, another Proton-M rocket, this time carrying the JCSAT-11 spacecraft, failed. On this occasion, a wiring fault prevented the first stage from separating from the second stage. A subsequent launch was successful.

On March 15, 2008, Proton-M suffered its second failure in six months, when it left the AMC-14 satellite in a useless orbit after the second burn of the Briz-M upper-stage shut down prematurely. The failure was caused by a ruptured exhaust gas conduit, which led to a shutdown of the turbo pump feeding the Briz-M engine.[6] Krunichev Space Centre proceeded to make modifications on the Briz-M engine and also completed a detailed quality assurance review.[7]

On August 19, 2008 Proton-M successfully launched one the biggest commercial satellites ever built - the Inmarsat 4 F3. After three failures in three years, the successful outing for the Inmarsat satellite was deemed essential to maintain market confidence in the Proton-M rocket, according to the BBC."

The Proton [in general]:
Total launches 335
Successes 294
Failures 41
Maiden flight July 16, 1965
http://en.wikipedia.org/wiki/Proton_(rocket)

In generally speaking the Proton and Proton M are not highly successful, but not horrible.