Answer:
   
   A common claim is the Reform rejects most of Maimonides 13 Principles
   of Faith. The real answer is: "It depends how you look at it". In some
   interpretations, Reform accepts many of the articles. In other
   interpretations, Reform does not. Part of this is due to the freedom
   of belief and practice that characterizes Reform Judaism.
   
   In examining this question, it is worth exploring why the question is
   relevant at all. According to "The Jewish Encylopedia", Judaism cannot
   be said to possess "Articles of Faith", as is found in Christianity or
   Islam. The encylopedia notes that: Many attempts have indeed been made
   at systematizing and reducing to a fixed phraseology and sequence the
   contents of the Jewish religion. But these have always lacked the one
   essential element: authoritative sanction on the part of a supreme
   ecclesiastical body. And for this reason they have not been recognized
   as final or regarded as of universally binding force. Though to a
   certain extent incorporated in the liturgy and utilized for purposes
   of instruction, these formulations of the cardinal tenets of Judaism
   carried no greater weight than that imparted to them by the fame and
   scholarship of their respective authors.
   
   Acceptance of Maimonides's Thirteen Principles of Faith is not
   required by halakha, and in fact prominent Jewish authorities both
   before and after Maimonides have offered a number of different
   formulations of the principles of Jewish faith. The successors of
   Maimonides, from the thirteenth to the fifteeneth century--Nahmanides
   , Abba Mari ben Moses, Simon ben Zemah, Du ran, Isaac Arama, and
   Joseph Jaabez--reduced his thirteen articles to three: Belief in G-d;
   Creation (or revelation); and in providence/retribution.
   
   Others, like Crescas and David ben Samuel Estella, spoke of seven
   fundmental articles, laying stress on free-will. David ben Yom-Tob ibn
   Bilia, in his "Yesodot ha- Maskil" (Fundamentals of the Thinking Man),
   adds to the thirteen of Maimonides thirteen of his own. Yedaiah
   Penini, in the last chapter of his "Behinat ha-Dat," enumerated no
   less than thirty-five cardinal principles.
   
   In the fourteenth century Asher ben Jehiel of Toledo raised his voice
   against the Maimonidean Articles of Faith, declaring them to be only
   temporary, and suggested that another be added to recognize that the
   Exile is a punishment for the sins of Israel. Isaac Abravanel, his
   "Rosh Amanah," took the same attitude towards Maimonides' creed. While
   defending Maimonides against Hasdai and Albo, he refused to accept
   dogmatic articles for Judaism, holding, with all the cabalists, that
   the 613 commandments of the Law are all tantamount to Articles of
   Faith.
   
   However, note that while no one formulation of a creed is accepted by
   all, certain elements of faith are accepted by all traditional sources
   and considered binding by traditional movements: the existence of one
   G-d, divine revelation of Torah on Sinai and others.
   
   That said, here is one interpretation of how Reform addresses the
   "Articles of Faith":
   
    1. G-d exists and the existance transcends time. 
       Reform agrees with this. The 1999 Statement of Principles says:
       "We affirm the reality and oneness of G-d, even as we may differ
       in our understanding of the Divine presence."
    2. G-d is one and there is nothing like G-d.
       Reform agrees with this. As the previous quote from the statement
       of principles said: "We affirm the ...oneness of G-d".
    3. G-d has no semblance and is bodiless. 
       Reform does not dictate a form for G-d, noting (as in the previous
       quote from the Statement of Principles): "[We] may differ in our
       understanding of the Divine presence." For almost all Reform Jews,
       G-d is treated as without semblance or body.
    4. The existance of G-d preceeded creation. 
       Reform doctrine does not contradict this statement.
    5. G-d is eternal and prayer should be directed to G-d 
       Reform agrees with this. The fact that prayer should be directed
       to G-d is captured in the 1999 Statement of Principles in the line
       "We respond to G-d daily: through public and private prayer...".
       The statement makes no statements, but does not contradict, the
       eternal nature of G-d. It does state: "We trust in our tradition's
       promise that, although G-d created us as finite beings, the spirit
       within us is eternal."
    6. G-d communicated with prophets 
       Reform agrees with this, as it holds with divine inspiration.
    7. The prophecy of Moses was true, and that he was the chief of all
       prophets, both those before him and those after him. 
       Reform agrees (in some sense) with the first clause, but has
       replaced the second clause ("chief of all the prophets") with the
       theory of Progressive Revelation. For Reform Jews, the prophecy of
       Moses was not the highest degree of prophecy; rather his was the
       first in a long chain of progressive revelations in which mankind
       gradually began to understand the will of G-d better and better.
       As such, the laws of Moses are held as strongly binding as they
       are in traditional movements, and it is today's generation that
       must assess what G-d wants of them. This view has been affirmed
       from classic Reform to the present (Gunther Plaut, Eugene
       Borowitz, Walter Jacobs, etc.)
    8. The entire Torah now in our hands is the same one that was given
       to Moses. 
       Whereas traditional Jews view the Written Torah as the same that
       Moses taught, for practical purposes, plus or minus scribal
       errors, Reform (as well as Conservative and Reconstructionist
       Jews) take a different approach. These liberal movements accept
       the results of biblical scholarship, and archeological and
       linguistic research. They accept that the core of the Torah may
       indeed have come from Moses, but that the document that we have to
       today has been edited together from several documents, and assumed
       the final form that we know in the time of Ezra (about 440 BCE).
    9. G-d will never change Torah. 
       Reform actually agrees with this. However, Reform believes that
       what was written was expressed in the language/context of its
       time, and must be reinterpretated for the language/context of
       today. Hence, Torah doesn't change, but our interpretation and
       understanding of it does. This is captured in the 1999 Statement
       of Principles in the line: "We cherish the truths revealed in
       Torah, G-d's ongoing revelation to our people and the record of
       our people's ongoing relationship with G-d."
   10. G-d knows humanity's thoughts and deeds 
       Reform's High Holy Day liturgies retain these concepts. In the
       past, Reform has removed from the liturgy those concepts that are
       incompatible with Reform (such as the nature of the Messiah).
       Hence, this concept remains compatible with Reform.
   11. G-d rewards and punishes 
       Reform's High Holy Day liturgies retain these concepts, leading to
       the conclusion that this concept remains compatible with Reform.
   12. G-d will send a messiah. 
       Reform holds with a concept of a messianic age, as opposed to an
       individual. The traditional messianic notion is not part of
       Reform.
   13. G-d will revive the dead. 
       In the literalist interpretation, this is not a Reform belief.
       However, Reform does hold with alternate approaches to fulfilling
       the underlying prophesies.