Insh'a Allaah, this is the Jalaalud-Deen Roomi I am enquiring about. Can you quote what the scholars have said about him and whether we should read his books as his books are in English?
JALAALUD-DEEN ROOMI (1207-1273 A.D)
Jalaaluld-Deen Mohammad Ibn Mohammad Ibn Mohammad Ibn Hussein al-Rumi was born in 604 A.H. (1207/8 A.D) at Balkh (now Afghanistan). His father Baha al-Din was a renowned religious scholar. Under his patronage, Rumi received his early education from Syed Burhan-al-Din. When his age was about 18 years, the family (after several migrations) finally settled at Konya and at the age of 25, Rumi was sent to Aleppo for advanced education and later to Damascus. Rumi continued with his education till he was 40 years old, although on his father's death Rumi succeeded him as a professor in the famous Madrasah at Konya at the age of about 24 years. He received his mystical training first at the hands of Syed Burhan al-Din and later he was trained by Shams al-Din Tabriz. He became famous for his mystical insight, his religious knowledge and as a Persian poet. He used to teach a large number of pupils at his Madrasah and also founded the famous Maulvi Order in Tasawwuf. He died in 672 A.H. (1273 A.D) at Konya, which subsequently became a sacred place for dancing dervishes of the Maulvi Order.
His major contribution lies in Islamic philosophy and Tasawwuf. This was embodied largely in poetry, especially through his famous Mathnawi. This book, the largest mystical exposition in verse, discusses and offers solutions to many complicated problems in metaphysics, religion, ethics, mysticism, etc. Fundamentally, the Mathnawi highlights the various hidden aspects of Sufism and their relationship with the worldly life. For this, Rumi draws on a variety of subjects and derives numerous examples from every- day life. His main subject is the relationship between man and God on the one hand, and between man and man, on the other. He apparently believed in Pantheism and portrayed the various stages of man's evolution in his journey towards the Ultimate.
Apart from the Mathnawi, he also wrote his Diwaan (collection of poems) and Fihi-Ma-Fih (a collection of mystical sayings). How- ever, it is the Mathnawi itself that has largely transmitted Rumi's message. Soon after its completion, other scholars started writing detailed commentaries on it, in order to interpret its rich propositions on Tasawwuf, Metaphysics and Ethics. Several commentaries in different languages have been written since then.
His impact on philosophy, literature, mysticism and culture, has been so deep throughout Central Asia and most Islamic countries that almost all religious scholars, mystics, philosophers, sociologists and others have referred to his verses during all these centuries since his death. Most difficult problems in these areas seem to get simplified in the light of his references. His message seems to have inspired most of the intellectuals in Central Asia and adjoining areas since his time, and scholars like Iqbal have further developed Rumi's concepts. The Mathnawi became known as the interpretation of the Qur'aan in the Pahlavi language. He is one of the few intellectuals and mystics whose views have so profoundly affected the world-view in its higher perspective in large parts of the Islamic World.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

It is not the speciality of the website to judge people. Anyway, it is not permissible to read the books about the ideologies of a deviated person unless the reader has a sound religious knowledge and can distinguish between what is right and what is wrong. So it is not permissible to publish such books because it will be easy for the public to read them, and this could cause some misconceptions in their mind.

Jalaalud-Deen, born in Persia stated in his biography the Soofist view in his poetry and writings, and stated that the soofi Shamsud-Deen Tabreezi had the greatest effect on his life after he met him. So he abandoned teaching and kept himself busy in Soofism and established a method called: "Al-Mawlawiyyah". He gave music a special place in the celebrations of his followers.  

Allaah knows best.