Same here (OS X, Safari). It doesn't look much better in the demos either. Their demos include some truly horrific examples, like Linux, Firefox 24, Ubuntu: http://fontcombiner.com/docs/media/demo/linux_firefox_ubuntu...

I, like many here, prefer the original on the left both in my browser (Firefox 27 on Windows 8) and in the example you linked.

Most notably, to my eye, the text on the right has unappealing kerning changes.

A concrete example, visible in the screen-shot you linked: look at the words "little three" at the top right of the second paragraph. In the original rendering, the space between the pair of 't's and the 't' and 'h' pair is correct. In the modified rendering on the right, there is an excess pixel between the pair of 't's and the 't' and 'h' pair.

Uneven spacing of letters is one of the reasons I am unhappy when I use Chrome, since it still doesn't support DirectWrite on Windows [1].

[1] http://code.google.com/p/chromium/issues/detail?id=25541

Much prefer the left and in fairness so far I've preferred the non-fontcombiner version on everything I've seen.

Thanks for the screenshot, the sample just shows as browser-default fonts for me with Iceweasel.

Both of these have the horrible rainbow effects around the edges of the letters, presumably from sub-pixel anti-aliasing.

But I'm an outlier, basically the only way I can read text without serious eyestrain is aliased with good hinting. Somehow the "jaggies" which so distress most people are completely innocuous for me, while I can't tolerate any of the fuzzy/blurry look that most readers bizarrely call "sharp".

If you're on Linux, you might already have the Ubuntu font, and if so will get better results using it. In addition, Ubuntu is likely a decent font, where this will drive the most improvements is in fonts of single weights designed for a fixed size and not easily resized from body text to headline or display to body.

It seemed right to try to offer transparent comparisons for screenshots rather than cherry pick. Linux font rendering can vary a lot depending on how things are set up.

Same here. Here's a gif to illustrate: http://i.imgur.com/3AmIB8Z.gif

I agree. For me (OS X, Chrome, rMBP @ 1920x1200) the kerning is much worse for Font Combiner. The letter "l" in Varela Round, for example, has far too little space after it.

I agree. I'm not sure what kind of an algorithm they use for kerning, but it seems to ignore how letters interact optically. Pairs like "ve" and "ro" are set too far apart.