While I found the readings on this site to likely be engaging and possibly challenging for grade 4-12 learners (as noted in the Teacher's Guide, or grade 6-12 learners as noted in the About section), several aspects of the layout and, more notably, what seem to be problems with updates to the site would keep me for using it.
As of the writing of this comment, the Quizzes, Notes and Proof for each reading seem to be no longer accessible (users "not authorized to use this page"). The Speak Out chat section from the home page is also non-functional ("page cannot be found"). While the Tips-o-Matic option still leads to useful information on sentence to essay level grammar, it apparently was at one time meant to be able to be "turned on" for interactive assistance with readings offered on the site--this is no longer the case. Finally, while the Teacher's Guide offers sound suggestions for use in the classroom, it obviously has not been updated for some time, as it continues to list RealAudio as a "new type of computer software." Some continuing maintenance (e.g. the ongoing addition of new suggestions for classroom or student autonomous use) would be helpful here.