Does the book “Reliance of the Traveller” play a significant role in Islam?

Question

I sometimes see the book Reliance of the Traveller, or Umdat as-Salik, mentioned online (Wikipedia; Amazon). Judging from Google, it has found a role as a go-to manual for those who wish to criticise Islam, with the top hits including "Creeping Sharia", "ConCit", "Islam Exposed", "counterjihadreport", "Mapping Shari'a", etc. This may be predominately because of the book's online availability in English, and I would guess that native English speakers tend to have a more Islam-negative attitude than the general population.

Question: Does the book "Reliance of the Traveller" play a significant role in Islam?

I found an online Shafi'i fatwa which gives the book a glowing review:

It is really hard to praise this book enough. It stands, without equal or competitor, as the primary Sunni manual of Islam in English. -- Moustafa Mounir Elqabbany, Qibla.com, sourced from IslamQA.org

And one fatwa with a luke warm stance (outside of the Shafi'i fiqh):

There is no harm in Shaf'iee laymen studying the book provided they refer to a qualified and reputable Sha'fiee Mufti in personal fiqhi matters. As for Hanafi laymen, it is not advisable to study the book since it can cause confusion and lead one towards Talfeeq, i.e. picking and chosing between the different Maz'ahib. This is Haraam as it involves probing in matters of Shari'ah without possessing the authority to do so. -- (Mufti) Abdullah Patel, MuftiSays.com

Wikipedia writes:

...This translation has led to this work becoming influential among Western Muslims. -- Nuh Ha Mim Keller

So maybe it's important in the Shafi'i madhhab, and growing in influence among Western Muslims since it's in English and easily downloadable.

Now having read a small part of the book (it's very long), I'm finding it is quite a handy reference.

Answer 1

All perfect praise be to Allah

This answer might not fully answer your question, but i will try to address the problem in general.

As basics we all know Islam is based on authentic references in form of Quran/hadees/aasaar etc. If anyone collects them, analyzes them, understands them and works hard on them to provides us with something easy to understand in layman form. That's great, we must appreciate and benefit from it.

The author should be from any school of thought from sunni schools(his basic beliefs should be right, so he does not mix anything wrong in your beliefs, which is base for our all doings to be accepted). This is for general public. However, if you are a researcher and understand all the things and it's unlikely something wrong will get mixed in your heart and make you astray, you HAVE to read all kind of books from all kind of authors from any school and any religion.

The only responsibility reader has got is to not get stick with any view author has given. Keep the eyes and heart open, to accept the possibility that he can be right in one thing and wrong in other thing. This does not mean if one thing is wrong in a book, whole book is unuseable. We should take what is right and leave where the author made any mistake.

Prophet (peace and blessings of Allaah be upon him) said: “When the judge issues a ruling, if he strives to work it out (ajtahada) and gets it right, he will have two rewards, and if he issues a ruling and strives to work it out but gets it wrong, he will have one reward.” Agreed upon

Humans are supposed to make mistakes, we can't expect anyone to be perfect in all his rulings and matters. This is the only thing which needs to be taken care of, if we follow this rule than we will be fine.

کل بنی آدم خطاءٌ و خیر الخطائین التوابون۔
All the sons of Adam err, and the best of those who err are those who repent. [Jami At-Tirmidhi: 2499]

Now, coming to the ACTUAL question. Yes, this book is an important book in shafi school، it presents shafi view in all its matters. So, expect it to be this way. It is perfect if you follow shafi mazhab, and it's still good reading if you don't and want to research more, not all matters are different, in-fact not even half the matters are different. You just need to understand basics to prefer one view over other.

And Allah knows best.