I used this book for planning and for advice a one month period of travel through Eastern Europe. Any book that tries to cover so many countries is going to be a compromise between very precise information and a lot of general information. I found that the Lonely Planet Eastern Europe has achieved a good compromise. For example, even a city such as Klaipedia, Lithuania has a few pages written about it even though it is not as popular as Kaunus and Vilnius. However, if you wanted more information about an even smaller city, you are out of luck since just a few cities are mentioned. The history sections are good introductions to each of the countries and the hotel reviews are helpful in planning. However, there still is key information missing. Key information such as that you must purchase a ticket for your backpack for the public transportation in Poland or you will be fined. A review of the LP web site shows lots of backpackers complaining about this, but the book does not include the warning. Also keep in mind that as Eastern Europe goes through rapid changes with membership in the EU and more and more people visiting, the whole travel industry will be changing. More hotels will be available and more people and places will be more accommodating for people speaking English. Therefore, any guidebook is going to have a difficult time keeping up to date on everything. Overall, I would recommend the book for travel through a number of Eastern European countries. However, if you plan to concentrate on just one or two, you may prefer to purchase country specific guides instead so that you have more information.
I had the fifth edition and thought it would be nice to be up-to-date for my next holiday with this 7th edition. That proved to be a mistake. LP has added a lot of countries (the Baltics, Belarus, Ukraine, Moldova, Moscow and Petersburg) without adding pages. As a consequence the information about the other countries has been reduced. For example Albania went from 40 to 25 pages. So if you don't have the guide I can still recommend it because I generally like LP. But if you have an older edition you should think twice about upgrading.