Wikipedia, as usual, sums it up nicely:
Often regarded as the first important European jazz musician who made major contributions to the development of the idiom, he is also revered by guitarists worldwide as among the foremost exponents of the instrument. Reinhardt invented an entirely new style of jazz guitar technique (sometimes called ‘hot’ jazz guitar) that has since become a living musical tradition within French gypsy culture. With violinist Stéphane Grappelli, he co-founded the Quintette du Hot Club de France, described by critic Thom Jurek as “one of the most original bands in the history of recorded jazz.” Reinhardt’s most popular compositions have become jazz standards, including “Minor Swing”, “Daphne”, “Belleville”, “Djangology”, “Swing ’42”, and “Nuages”.
Here is a bio that accompanied Ken Burns’ jazz documentary on PBS. Reinhardt’s Wiki is appropriately called Djangopedia. Great examples of Reinhardt’s genius, as the Wikipedia entry suggests, are Nuages and Minor Swing. The video from the latter is from a version of Alice in Wonderland released in 1933. It doesn’t appear that the song was part of the soundtrack, but it is interesting. The actress is Charlotte Henry. Honeysuckle Rose may be more familiar to American audiences. An item on Reinhardt should mention Stephane Grappelli, who co-founded Quintette du Hot Club de France. Grappelli, in a long and distinguished career, played with everyone from Yo Yo Ma to Vassar Clements.
The above short bio has some footage of Reinhardt, which seems to be rare.