Krause Standard Catalog 1901-2000 is simply the world standard of coin catalogs for the period. Unless your collection is highly specialized within a very small region or you collect coins which Krause does not list as such (such as German notgeld or tokens) this is a catalog you must have in your private library. 2010 edition includes also CD version so you don't have to carry around this rather bulky volume if you travel with your laptop.
The countries are organized in alphabetical order and within countries coins are listed by denominations with most coins presented in black and white pictures. Every coins is priced in at least three grades (except for parts of the US listing where commemorative coins are apparently worthless below AU grade while other coins are priced in eleven grades) with prices basically reflecting current market trends.
In short - if you collect world coins and you don't have a copy, you simply should stop reading at this point and order one immediately. However, if you do have a fairly recent copy you should think twice before doing anything. The prices have been updated here and there. Russia, Belarus and Ukraine (if you collect Eastern Europe except Poland, you are in for a nice surprise!) were, Germany and France not necessarily while some markets have changed greatly over last few years. Let's then take a look at Poland which has not been seriously updated for a decade. The key issue for post-1990 coins #306 King Sigismundus (still listed at $10 for Unc) will actually cost you at least $200 (unless you know a dealer who can't use ebay). Any 2 zlote commemorative coin from 1995 will cost at least $30 - Krause offers $3,50 for most. Prices of silver coins are a bit closer to reality but only some were actually changed: #314 Lidzbark castle is still listed at $50 while market price is closer to $400.
It is fairly understandable that updating all the prices of the whole catalog is a major task but it seems that the editors are a bit too certain that at least one part of their job is done - that their catalog includes all coins issued within the period. Well, it doesn't... I found at least two omissions. There are four 1 pound coins from Cyprus missing - one from 1999 and three from 2000. Copper 1999 3000 bolivares from Venezuela commemorating the new Mint is missing although silver 6000 bolivares coin issued on the same occasion is included. You will probably find some more missing pieces.
My conclusion - if you have a fairly new edition already (especially the 2009 one which also has the CD) you can stick to it for a while. The editors simply did not update this issue to such a degree that would justify the costs of your updating your library.