Inkscape is ok. It has serious issues though - pretty terrible performance, confusing UI, still requires X11 on Mac, etc. Probably still the best free SVG editor but I'm not sure I'd go so far as to call it good.
The performance issues are real. Just open a complex SVG, select a few thousand elements with a rubberband selection, and see how everything slows to a crawl as it tries to render the outlines. If that is not slow, try manipulating that selection (e.g. scaling, rotating).
Most of the time, when I run InkScape to edit an existing .SVG, it's because I want to just select and drag a few vector endpoints a bit to one side or the other to make minor tweaks. I'd venture that's true for most users. However, it doesn't seem to be the default behavior. I always have to remember how to get into the right selection mode, because the authors seem to think I most likely want to drag the entire image around. Why I would want to do that, I can't imagine, but that's how it works.
That's a problem for many common actions -- for instance, I normally want to resize the view box to enclose the content tightly before saving an edited file, so why is that common action buried multiple layers deep in the UI? File->Document Properties->Page->Custom size->Resize page to content->Resize page to drawing or selection->Seriously? It's almost easier to do this in a text editor.
Finally, people who write apps that don't remember their previous desktop window size and position, but that instead auto-size themselves to cover the entire screen every time they're launched, should die in a grease fire. Unnecessarily-aggressive hyperbole aside, this kind of obvious forehead-slapping behavior is never good news because it means that the maintainers don't use their own app.
All that aside, InkScape is really a very powerful application that could be a lot harder to use. A great deal of hard work has clearly gone into it, and at the end of the day it is free software, so it's hard to complain without seeming ungracious. If it weren't such a great app, it wouldn't be worth criticizing at all.
