I have a degree in oriental languages and am an avid collector of language study books (I've got at least 30 TY ones) and this is not the best of them - but it's not the worst either.I'm aware that the author is the leading lecturer of Thai in the UK, but that doesn't necessarily mean he's the best writer of a Teach Yourself book (He should perhaps have looked as his colleague Dana Healy's TY Vietnamese for an example of a better TY book). That's not to say there isn't good stuff in it - there's just not enough vocab and perhaps even grammar - and I don't see the point in having a short one-way dictionary in the back - all the new content should be given in each chapter so you don't have to go scouring around for it (but then you should get a separate dictionary anyway).
It's probably best to get the tape, but the actors on it are rubbish and speak with no emotion, so it's a bit of a drag.
One bug bear I have about the transliteration is that it's written for "southerners" (as in the home counties of England).
Now I don't pronounce the letter "u" like an "a" like southerners do, so when I first read out the words like "yung-ngai" or "nung" as a northerner it didn't make sense to the Thais - that's we have the IPA isn't it?!, but I do like the way he writes "gk" and "bp" for those inbetween consonants.
The main disappointment with this book is the lack of content. I've seen the Colloquial Thai one (which is worse than this one), and that has much more in it: but is not presented well; doesn't develop enough in the early chapters; and doesn't contain the script much.
This TY book does have plenty of script and it's in a nice font and conveniently written on one side of the romanised text, so you can cover one side and challenge yourself.
I actually first tried to learn Thai with a Lonely Planet and Rough Guide phrasebooks (which have better romanisation) out in the sticks with no dictionary, and I think this TY book could benefit with some of that phrasebook structure giving you a few real-world useful sentences and phrases to get started with.
I've taken this book with me to Thailand, and inflicted it upon my Siamese family, and it's OK, but frankly it's only a little more useful than the Rough Guide phrasebook - which is written by the same author! Hence the title "Could do better" - because he obviously can (My Siamese family also preferred the Rough Guide book, because they could use it a bit too!)!
In general, In terms of content TY books could do with being a bit more like phrasebooks and being in ring-bound format because the pages nearly always start to come out after a while, and you need a large pair of bulldog clips; and they could also do with having the nice paper quality of the 90's editions - the new yellow ones hide their horrid thin and rough yellowy paper behind pretty photos - a return to the nasty blue ones of the '80s. (I suppose they'll end up being 100% software things anyway eventually, but if they're going to make paper books they could at least improve the quality).