Hi T.,
My little boy (now 2)is exactly like Thea's. He is constantly taking the floor apart and so in addition to the toys to tidy every day, I have to go in search of letters and bits of letters.
The upside of it is that he knows several of his letters because of it and will bring me an O or a number 4 or whatever if I ask him.
To be honest though, I could've taught him that in a different way and saved myself a lot of trouble, so I would get something solid with a pattern instead if I was doing it again.
If you decide you don't mind the puzzle pieces aspect of it, then it is good quality and keeps my little boy warmer than the hard wood floor would. It also adds a layer of padding, so when he decided to climb his book shelf and fell off he didn't really hurt himself.
The only thing I would really recommend is to get a unit with several drawers in it, to help keep things organised, but also so that your little one can find things easily. I have this unit http://www.homebase.co.uk/webapp/wcs/stores/servlet/Produ... (which I bought in England, but I'm sure you can find something similar. You might want to get something more neutral if it's in your family room ) and each drawer has a theme - cars, blocks, musical instruments, etc.
Good luck. Have fun.
D.