I'll say one thing though, which is that my opinion of unifix cubes seems to not have changed in the slightest during the past few decades. Unifix cubes are stupid. They're like Legos, except they only connect in one direction. The only thing you can build with them is a damn line. I've now learned from my little google exploration that they can apparently be used for learning about place value, bar graphs, and patterns, among other things. None of this purposeful-use-of-unifix-cubes stuff seemed to happen much in my school though.
Rather, unifix cubes were in one of 30 or so cigar boxes of "manipulatives" from which we could choose. Had I been about 10 years older when I was in the kindergarten room, I'd surely have been stuck on a shelf labeled "manipulatives," but as it were, the boxes each contained a set of some sort of educational toy.
The most popular sets were little wooden houses, fake shrubbery, little cars, coins from various countries (each one housed in a big square of laminate, presumably as some sort of anti-theft precaution), kaleidoscopes and little farm animals. The least popular set was the unifix cubes. Even the other mundane math toys like geoboards*, pattern blocks and Cuisinaire rods were preferred over the unifix cubes. The kid who ended up getting called up last to choose a box -- thereby ending up with the unifix cubes -- was always looked down upon.
I do wonder if maybe the actual point of unifix cubes was to teach us kids that, hey, if you don't sit in your seat and politely wait for your turn, you end up having to be seen with unifix cubes on your desk for 20 minutes. It wasn't a totally foolproof system though, because there were a few times that some kid actually went up and chose the unifix cubes. This was a relief for whoever had screwed around the most prior to manipulatives time, but it signalled to the whole class that, well, you can make your own inferences about someone who willingly chose substandard Legos over kaleidoscopes.
*Mind you, this was in kindergarten, before we discovered that geoboards made awesome slingshots. I'm guessing the reason unifix cubes disappeared after kindergarten is because they'd actually make great ammo.