I am thinking of getting an ebook. I would welcome any advice, tips etc as to the best buy

Get an android phone, (a magic is around £100) apps available for reading eBooks, and also on-line books, I read loads on train, other places cause your "Reader" is always with you...

Despite its convenience a mobile phone isn't an ideal reader.

Readers have a different screen tecnology that uses reflected light with better contrast under most viewing conditions and a longer battery life. They also have a larger screen.

Have you consulted this comparison?
http://en.wikipedia.org/wiki/Comparison_of_e-book_readers

I use Amazon Kindle (on my Android phone) and it works great. I would think that an actual Kindle would be even better given the larger screen. But even on the Android, you can adjust the type size, the contrast, etc.

If you want it purely as an ereader and you will be reading a lot then it would be advisable to get an Amazon Kindle. As Galaxiom said there is a special type of screen for ereaders which is more gentle on your eye causing far less strain. In the past Sony ereaders have had large failure rates (search google to see how many complaints there are) but the Kindle has a good reputation and is a reasonable price. I am not sure what other alternatives there are to the Kindle.

If you have more money and would like a multifunctional device then perhaps consider an iPad or await the iPad 2 which will have a much higher screen resolution. The iPad may strain your eyes if you read for long periods due to it using normal screen technology but it can surf the internet, use apps etc.

I personally feel a phone screen will be too small to read, even if you can zoom in. I have the iBooks app on my iPhone 4 but I wouldn't want to read a novel using it.

The best thing is to try the devices out before you buy, I am not sure where you could demo a Kindle or other eReader but you could try an iPad inside any Apple store.

Just bought my wife a Kindle, the only downside to it is that there is no backlight on it.you can get a protective cover that has a built in light for nighttime or bad light reading but it comes at a price nearly half the cost of the Kindle itself.

What does everyone think of the Nook? I have seen it in Barnes and Noble and have wondered, it doesn't get as much press as the kindle.

Just bought my wife a Kindle, the only downside to it is that there is no backlight on it.

Well, real books don't come with a backlight either :D

Just download an audio book onto your favourite media player :D

Both my wife and Daughter love their colornooks. They have a backlight.
Downside is the battery does not last as long as the eInk readers.

how does this work? Do you have to buy from ebooks from a particular website for it to work on the phone or can any .pdf document work?

How come nobody even mentioned the iPad ? :)

To answer the above question, readers can read various types of formats. From epub to PDF, etc. You just load the ebooks on the device and that's it.

iPad is neat for magazine subscriptions, but for bookworms who loves to cuddle in sofa/bed when reading novels, kindle or nook is the best option - I like the latter, specifically nook simple touch.

I Love the 'Nook Tablet" good color and long Battery Life.