It really depends what your current level of knowledge is. In my experience, I didn't find a lot of info on that site that I haven't already gotten from other sources but, if you haven't done much research, it would give you a centralized resource for the info. However, the site layout is pretty convoluted so a significant time investment is required to explore it all. Also, you lose the advantage of being able to carry it with you on your trip like you can a good guidebook, which you could obtain for a similar price.
The touring plans all pretty much cater to "commando" touring so, if you need to see/do it all while there, you might find them useful. I didn't find much that catered to any kind of personalized or alternate park touring so that was a bust for me too.
Lot's of people seem to really like the site but, as a repeat and knowledgable visitor WDW, I didn't find much that was new or helpful to me and I was bothered by the fact that the site doesn't update some key event info until far later than other free sites.