I think it strikes a good balance between explaining things in layman's terms and providing the necessary technical details as well as citations, relative to, let's say, Master Tax Guide (which is a bit too abbreviated and fragmented in organization because it relies heavily on cross-reference).  It is more like QuickFinder, as Anna says.  There is a money-back guarantee, if I recall, so you can try both before making a decision which one is best for you (and your staff).

Agree with Rick that the state tax guide from The Tax Book is an excellent resource.

Since you mentioned tax research, my take on that is both The Tax Book and QuickFinder are good resources for basic research on a topic.  For more in-depth research, nothing really beats CCH and BNA as a one-stop shop.  Yes, a lot of the same material is available from the internet without charge but it will take a bit more elbow grease to scour the right places.