Islam, like all religions, is a highly complex cultural phenomenon. People try to lump all Muslims together and assume they all think the same thing, as if they were some vast lumpen mass. If they actually took the trouble to get to know some Muslims, and get to know a bit about Muslim culture, it would help.
There are lots of things to admire about Islam. The 99 names of Allah reflect different aspects of the Divine, such as compassion, peace, forgiveness, and subtlety. Muslims recognise other religions of the book as worshipping the same deity. The coming of Islam brought peace and stability and prosperity to the warring Arabian peninsula.
The Muslim world (Dar al-Islam) has traditionally been much more tolerant towards religious minorities within it than was true of Christendom (which either expelled or forcibly converted Jews and Muslims, and then tortured them and burnt them if they reverted to their previous religions). Under the Ottoman Empire, and in al-Andalus (Muslim Spain before the reconquista), religious minorities were tolerated - they may have had certain restrictions, but they could practice their religions. When the Crusaders took over Jerusalem, they slaughtered most of the inhabitants, including Christians, Jews and Muslims, so that the streets were running knee-deep in blood. When Saladin (Ṣalāḥ ad-Dīn Yūsuf ibn Ayyūb) took over Jerusalem, anyone who wished to leave was allowed to do so without let or hindrance. Saladin's noble and chivalrous behavior was noted by Christian chroniclers, and he became a celebrated exponent of the principles of chivalry.
The Renaissance in Europe happened because of the art, culture and science that came from the Muslim world. Muslim scholars had been gathered together in a group called the House of Wisdom under the Abbasid Empire to translate classical texts into Arabic. Muslim scholars not only translated texts but also wrote treatises on science, astronomy, astrology, medicine, mathematics, the arts, and so on. The names of many scientific instruments and areas of knowledge come from Arabic. Alchemy, chemistry, algorithm, alcohol, almagest, and so on. Many star-names are Arabic, or come from Arabic, and very beautiful they are too. The poetry and literature of the Arabs was also outstanding. There are still many Muslim scientists today. And also, Ibn Battutah, a medieval Muslim traveller from Morocco went all the way to China and wrote down what he saw on the way - he travelled much further and more widely than Marco Polo, and stayed longer in the places he visited.
The Arab world also had very advanced ceramic techniques - probably because of the emphasis on geometric designs in mosques, because of the ban on graven images.
Fairly early on in the history of Islam, there developed a difference in emphasis between two groups: the Sufis, whose emphasis was more mystical; and those who preferred the more legalistic side of Islam. Indeed, Islamic jurisprudence is complex and subtle. There are several different forms of Islamic law - so it would actually be very difficult to impose sharia on Muslim communities in the UK, because they all come from different places where Islamic law has developed differently.
Two major groups in Islam are the Sunni and the Shia. The Sunni derive all authority from the Prophet Mohammed; the Shia recognise a line of holy men who are descended from the Prophet.
The word "Sunni" comes from the term Sunnah, which refers to the sayings and actions of Muhammad that are recorded in hadiths (collections of oral testimony regarding Muhammad, collected not long after his death).
"Shia" is the short form of the historic phrase Shīʻatu ʻAlī, meaning "followers", "faction", or "party" of Muhammad's son-in-law Ali, whom the Shia believe to be Muhammad's successor.
Sufism or taṣawwuf is defined by its adherents as the inner, mystical dimension of Islam. A practitioner of this tradition is generally known as a ṣūfī. Sufis believe they are practicing Ihsan (perfection of worship) as revealed by Gabriel to Muhammad. The Sufis have produced a lot of really amazing mystic poetry, such as the poetry of Rumi and Hafiz; and many inspiring saints, such as Al Hallaj and Rabia. Their worship services (zikr or dikr, meaning remembering the name of Allah) are very beautiful.
Wahhabism is a conservative and fundamentalism form of Sunni Islam. It is particularly strong in Saudi Arabia. It has gained influence for various reasons over the rest of the Muslim world, partly because its adherents are very wealthy, and partly because of the rising hostility between the West and Islam, which creates a vicious downward spiral. Wahhabis also distribute a version of the Holy Qu'ran annotated with their interpretations of it.
There are aspects of Islamic practice which don't appeal to me. I believe the body is sacred, and sexuality is sacred, so the idea of modesty does not appeal to me. I support the right of Muslims to wear hijab (modest dress for both men and women; although in many Islamic countries it has been the modesty of women that has been the most policed and commented on). I disagree with extra emphasis being placed on hijab for women, which is the case in some Islamic countries, especially Saudi Arabia; but there are hijab codes for both men and women. If people want to indicate their devotion to their deity, good for them. I don't think it qualifies them for extra respect, but they should be accorded as much respect as anyone else, and I absolutely and unequivocally condemn violence against people observing hijab codes.
I also dislike the anti-gay rhetoric coming from some Muslims - but I also dislike the anti-gay rhetoric coming from senior figures in Christianity, which is currently considerably louder, or at least getting more media attention. I abhor the fact that in many Islamic countries, being gay carries the death penalty, and sincerely hope that this will change.
[Update: There are also advocacy groups for LGBT Muslims, and a prominent Muslim spokesperson who stands up for LGBT rights.]
As a vegetarian, I can't say I particularly like the slaughter of animals for festivals in some Islamic countries; but that's not really a core part of Islam. If you insist on eating meat, then I think dhabihah (the correct method of slaughtering meat so that it conforms with halal) is more humane. It says that you should bless the animal with the name of God before killing it, and the killing should be swift and humane. Muslims are taught throughout the Qur'an that all animals should be treated with respect and well cared for.
One of the interesting things about Islam is that it is all about the consensus of the ummah (the community); there is no Pope and no Archbishops. There is more than one imam. If you don't like the interpretation of the Qu'ran (a fatwa is an interpretation of the Qu'ran) that you get from one imam, you can go to a different one.
Just like any other holy book, the Qu'ran contains contradictory passages and bits that are confusing. There are many passages advocating peace, compassion and tolerance; there are also exhortations to violence. The same is true of the Bible. That is why exegesis is a delicate art and these books should be taken as a whole, not just quoted in bits taken out of context, and above all they should not be taken literally.
Like all other religions, there are fundamentalists in Islam. I don't like fundamentalism in any religion; but I have to say that Christian fundamentalists are just as dangerous as Islamic fundamentalists, if not more dangerous, because they have access to power and influence and money in one of the most powerful countries in the world, i.e. America.
Most Muslims just want to live in peace with their neighbours. They are mostly peace-loving and compassionate people - something that news programmes consistently ignore.
So, for goodness' sake, people, get educated about Islam. I have only skimmed the surface here, but it is a very complicated topic, just like all other religions.