On an introductory college-level, I don't know any books that beat Freedman & Kaufmann's "Universe" (latest couple of editions co-authored also by Robert Geller). I don't have my issue (6th edition, 2001) with me right now, but as far as I remember, it requires no more than entry-level college math and physics. The current edition is 10th edition (2013); eleventh edition can be pre-ordered on Amazon.
It doesn't get much in depth with each topic, but it is impressively extensive, and gets around everything from the Earth-Moon system to exotic objects and cosmology.
The writing style is also impressive. It is easily read, with a good balance between everyday and technical language, carefully introducing technical terms as they are needed. Headings and subheadings are short one-sentence summaries of the most important points in each (sub-)section, and important take-away points are well introduced in separate boxes. It is richly illustrated, has supplementary online material, and in general an easy read language-wise, but still serious and very thoroughly researched and fact checked.
Given that it is an introductory text book to an entire field, each topic is of course treated somewhat superficially. Do not expect to reach expert level with this book, that is not what it is meant for. It is, on the other hand, a very good, broad introduction to a large and dynamic field, and new editions updated with the latest advances in Astrophysics are frequently published.
I know this sounds a bit like a sales pitch; I have absolutely no stake in this book, and I think the price tag, at around a hundred dollars, is the only mention worthy downside to this book.