I've been using the Lee charge bar with my Auto Pro Disk for years.
Simply put, it is as accurate and as repeatable as either my RCBS Uniflow or my Belding and Mull, both of which are several orders of magnitude more expensive.
As others have said its biggest drawback is that it's not great for smaller loads because it becomes inconsistent. I've found that level to be about 4.5 grains of WW 231. Once I hit that point it is VERY consistent.
Some have said that the inconsistency comes about because at lower levels the hole in the bar doesn't line up well with hole in the powder hopper.
There are any number of solutions, one that involves using a soft eraser to create a block that effectively moves the charge bar hole foreward and closer to centered under the powder hopper, allowing the charge hole to fill accurately with smaller charges.
I've done it, and it works well but takes some fiddling to get right.