Last year's (2007) Penguin Guide was just a 'yearbook', covering new releases in the previous 12 months. This 1600 page 2008 edition is a general guide to 'the best' classical recordings from those currently available in the U.K. There are now so many classical CDs of such a high standard that the editors have had to make changes to previous editions. The main difference is that there is now a '4 star' rating for truly exceptional recordings. Also three starred recommendations now have a shaded box around them to make them stand out. There is a 'key' symbol for, er, key recordings. And there's a Rosette symbol awarded by an individual reviewer for CDs that have some special quality. I can't help but think that all these symbols will make things confusing for newcomers.
But on the plus side, the typesetting is much clearer, and the Guide is printed on better quality (though inevitably thin) paper now, making it easier to read than in the past.
As usual the reviewers are generally pretty reliable; musical judgement is of course highly subjective (I would never want Mahler conducted by Karajan; that hideous Mahler 5, more Mantovani than Mahler) but newcomers won't go wrong too often, and we seasoned collectors like to disagree from time to time. But there are some serious omissions for a Guide that was published in September 2007. The legendary recording of the Schubert String Quintet by the Aeolian Quartet with Bruno Schrecker (Regis Records, formally Saga) is missing. As is the Mahler 2nd Symphony in a stunning recording by the Budapest Festival Orchestra under Ivan Fischer (Channel Classics); a disc which has won many awards including a Gramophone 2007 Award! I could go on; I just don't understand how so many really excellent discs get missed. On the other hand, there's the occasional discovery; for me the wonderfully noble account of Tchaikovsky's Pathetique Symphony conducted by Vaclav Talich on Supraphon.
Overall, this is by far the most comprehensive guide around here in the U.K. I personally prefer the Rough Guide to Classical Music, complete with composer introductions and idiosyncratic articles, but that's very out of date now. So yes, if you want general guidance, this is a recommendable book.
And with so many classical recordings available, and still being turned out, it's reassuring to see that the death of classical music has been greatly exaggerated.