I've thumbed through it a few times and it looks to have some really great stuff! But I've never really used it extensively. I've pulled a few interventions and ideas from it here and there.

I hear a lot of positive things about it and the material seems very well organized, sorted, and easy to navigate. If you are looking into purchasing one but are unsure, you should see if you can borrow one from another school or district to check it out. Your ISD may have them to borrow as well.

Here are some comments on it from Amazon. These reviews seem very positive.

Some other reviews on the PRIM:
GoodReads.com

And another set of reviews from Amazon.

I think the reviews are probably indicative of all editions too.

I work at an ISD and lend them out to districts. They are quite popular and rarely sit on the shelf. I think they are a worthy investment.

Thanks for the first hand input! They look like they'd be worth the investment, and all seem to be positively reviewed, so it's great to get your feedback that they are indeed useful and worthwhile. Thanks for chiming in!