I'm a graduate degree'd engineer with a great appreciation for well designed tools, the owner of a handyman business who uses his tools daily to earn a living and a hobbyist woodworker. With that as background ...
I own a total of 3 track saw squares and this is by far the best designed, best built, and most accurate, but also the most expensive by a factor of 2.5x-4x. I've tested the accuracy of each of my 3 track saw squares and can confirm from firsthand observation that this is the most accurate. The SpeTool track square is also the only one that provides an actual accuracy spec ("guaranteed accuracy of ±0.01°"), while the others merely state "super crazy accurate -- trust us!". I can't measure the accuracy of my SpeTools track square, but as I stated above it is the most accurate of my track saw squares in my testing.
I recently used the SpeTools track square in fabricating some custom shelves for a client. The clamp mechanism does an excellent job of aligning the tool with the edge of the track. The tool is CNC'ed from a heavy aluminum plate that certainly appears to be robust and shouldn't easily get deformed in use. The hardware on the tool is all very good quality and functions extremely well. This is a large (long) track square, which allows for precise alignment with the edge of a board or sheet, but also makes the tool heavy and a bit clunky in use. There is a small "finger" support that sits on the edge of whatever is being cut to prop the body of the square up at the same height as the work-piece. Some track squares include support on both the front and back of the square, which I prefer.
All in all this is a high quality, very accurate track square, but that quality comes at a correspondingly high cost. For me the cost is justified, since I earn my living with my tools. A hobbyist may well decide a track square that's 1/3 the cost and performs almost as well is a better deal for their needs.
Products ease of use.
I have another right angle track saw attachment that looks like a child's toy compared to this one. For the record I have SpeTool pieces ranging from router bits right up through to their router sled. Their stuff is generally solid. Having said that, I haven't had a chance to use this yet. It does fit on my third party Makita compatible track saw guide nicely, but it is going to take a while to really put it through its paces.
The aluminum is really sturdy. The size of this guide really floored me. It's absolutely bomb proof in terms of the thickness of the aluminum. The anodization is nicely done but the real star is the rigidity of the frame.
I have a repeating order that has a somewhat detailed pocket and then a 0.75 contour cutout. This bit does just what I need and is holding up well.
Good products and a 5 stars customer support