At first, I was hesitant to pay the extra 30USD to get these blocks when I can opt for a cheaper version of basically the same thing in Amazon. However, if you look at reviews, those cheaper options come with foam that aren't as dense. They are either too soft that it sags, or the fabric isn't sewn correctly that they fall apart after one use with rambunctious toddlers.
Upon receiving these, I was surprised to see that they come fully assembled in a huge, light-weight box. I thought the foam were vacuum-packed and I had to stuff them in the covers. But no. They were ready to go once you open the box! The foam was top quality, the fabric held up to a teething 11 month old, and the seams are still together after a week of use. My son has enjoyed climbing over them, using them as step blocks to get to the sofa (with help), problem-solving when I use these for obstacle courses, etc. Time will tell if they are as durable as they seem, but I am pretty happy with how dense the foam is. The fabric is also easy to clean. Drops of milk is inevitable with a baby, but with these, just wipe away with a damp cloth.
When my son perfect climbing over these, I'm sure these will be perfect for stacking, and eventually, building forts. I hope they will survive years of abuse.
Tips: The bottoms of some of the blocks have an anti-slip layer. However, they do not function as well on playmats. So when a baby climbs over them, they will inevitably slip away. Since they should be used with adult supervision anyway, just hold it against a surface, and you're golden.