A friend of mine had one and when I saw how easy it was to transport his kayak (while I carried mine), I knew I had to get one. The cost is reasonable and the quality of materials is very good. I suspect I'll have this a long time.
This cart is inexpensive, well made, and fits my 12ft kayak precisely right. Three straps hold it securely, but are quickly installed and removed. Probably a larger-wheeled cart would be required for moving over soft terrain, like sand, but for short hauls over most surfaces, it is a handy helper.
I purchased this because I have been carrying my Pamlico 120 almost half a mile to and from the river to paddle. This cart straps on very simply and works well and stows behind the seat while paddling.