I have the 17" one and love it. I used a 50% off coupon though.

I have both sizes and I use them both equally. No problems slipping or spinning.

I bought the 12" at JoAnn's it was 50% off, love it, new to quilting so don't have any idea yet if I needed larger one.

I got one when they first came out and have used it heaps. It is great for cutting circles and small pieces, I use it for template stuff. If I am doing strips or sub-cutting I use my normal mat.

I do the same if cutting my strips or subcuttin. I have one of those craft tables (actually, I have 2) with the fold down sides. I use both my 24" mat and I have a 37" mat that I bought at JoAnn's when it was less than $20, use that one the most.

i made my own for about $12.

i bought a lazy susan from ikea for $4 and then i use my older cutting mat that i got on sale at joanns that i didn't use any more.

i cut the mat down to fit the lazy susan and glued it to the top.

it works great!

I have the 12 inch Olfa one and LOVE it! I keep it on the ironing board to square up blocks and.....
I had another brand (June Tailer) that I HATE! It is on a metal lazy suzan base and has a soft center, and the glue gets soft and the parts separate!

Be mindful of the brand you get! I did use coupons for both!