For me, the key to feeding bees emergency sugar in winter is to put the sugar in long before the bees need it (I do it in late November). It can be a gong show once the bees are hungry and clustering above the top bars, in which case these sugar bricks are pretty convenient.
If I do this again, I’ll make the bricks larger. Dry sugar on newspaper over the top bars is still my favourite method of feeding the bees in winter because a large amount of sugar dumped in all at once will keep the bees alive until spring and I won’t have to mess with them again. But I definitely appreciate the convenience of being able to slip the no-cook sugar bricks into the hives as a stopgap measure.
UPDATE (24 hours later): Well, the bees in at least one of the hives are eating the sugar brick.
March 2nd, 2016: I use this same method to make sugar cakes in the Episode IV.
July 2019 Postscript: I said, “Dry sugar on newspaper over the top bars is still my favourite method of feeding the bees in winter,” but it’s not. I use sugar bricks exclusively these days because, for me, it’s much easier to slip in a brick than it is to open the hive and pour sugar in.