I ordered some of their "Total Substrate Pellets" a few months ago and waited until now to write a review (mostly cuz I'm lazy, but also cuz I wanted to see how the plants did).
I must say, I'm very impressed. The order arrived very quickly and, as I should hope, was what I ordered. The pellets come in packages of 75 for $10.99- seemed like a good deal to me so I though I'd give it a try.
They all come in a pill bottle and are quite a bit smaller than the Seachem Tabs I had previously used. However, the Seachem ones are supposed to last 3-4 months, whereas these are supposed to be replaced every month. I'm a slacker, I replace them every 2 months and haven't had an issue. Another note is these contain chelated iron, whereas the Seachem ones don't.
My rooted plants have been doing very well with this fertilizer and my overall experience with the site was very good. I'm not sure I've noticed much increased growth as compared to the Seachem ones, but it's definitely good, and way, way cheaper!