The cons first. For one, it's somewhat unstable. A number of times I've had a few pieces pop out during use and fly across the room. It doesn't usually end up causing a full explosion, but it is a consistent problem that I haven't been able to fix with any combination of tension adjustments. A delicate touch is required at times, so maybe not so good for younger kids. Secondly, the quality control is questionable. Some of the pieces have very rough edges and protrusions leftover from manufacturing, and while the sticker quality is decent, the application of those stickers is iffy. I bought one of each color. The white one had nearly perfect stickers, the black one had air bubbles like crazy. Nothing a little sandpaper and restickering won't fix, but that's time out of your day and is a point worth noting.
Now the pros. It actually turns very nicely. As long as you take care with alignment, it's a pretty easy to manipulate puzzle. Lengthwise turns are a bit clanky, but even so the cube almost turns itself. It also makes for a decent challenge as far as the puzzle itself is concerned. Shapeshifting and parity can be found here, but a similar solve solution for the traditional 3x3 can be applied at times.This makes it quite easy to pick up and progress with if you're familiar with twisty puzzle in general, but offers enough of an additional challenge to warrant a purchase.
In summary, Calvin's 3x3x5 cuboid is a decent puzzle with some minor quality control and stability issues, but is still a solid choice for those interested in cuboids.
