Nobody liked the visualization. I called it a blobby thingy and wondered why not a bar chart, mungo, baltassar, bluehorseshoecrab all expressed dislike as well. It's a type of 'radar plot', the following link goes into detail on why such plots can be bad and suggests barchart/lollipopcharts instead.
data-to-viz.com: The Radar chart and its caveats
That was my gut reaction as well: colored bar charts with mouseover and drilldown capability can be very informative. They did use a type of bar chart elsewhere in their site, but again got carried away.

I give them kudos for trying, in fact they ask for feedback on some of their visualizations, so maybe they'll eventually get it right. I've looked at a lot of other sites now, and all seem to be either oriented to short-term traders i.e. "We put a mess of indicators on a mess of charts for you!!!", or else are excuses for idiosyncratic stock screeners "We'll pick winners for you!!!". The part I did like of the simplywallstreet site was the interactive graphics (not just in the blobby thing that no-one liked) and that they made use of defaults (pre-populations). Admittedly, because the choice of defaults, e.g. for competitors, is automated, then this often won't be right but getting say 2/3 of them right can be useful in sparking ideas. If a site is easy to use, and you can easily change choices to something else, then I'm ok with it.

What I'd personally like to see is a site where you can pull up a company's fundamentals and expore them graphically and in drill-down fashion. Have some reasonable defaults for barcharts that convert the gross numbers to percentages and displays them, but you also have the ability to change the denominator. Show groups of things at once, e.g. hit a "Debt" button and it'll show you graphics for present short-term, long-term, and type of debt etc, then it'll have a button to graph same ver time. Similar for a "Profitability" button, and it'll show you different views of profitability (ROE, ROI, ROS etc). Everything is always customizable so you're not limited to preset defaults, but there always are defaults so you don't have that "writers block, blank page" problem. Maybe you can set up your own profiles for looking at different classes of stocks, e.g. your favorite measures may be different for 'value' stocks compared to growth. Have defaults for competitors, but with ability to change them. Ability to graph fundamental ratios over time, e.g. 10 years and you're started off with some reasonablbly informative set of defaults that are easily changed. Ideally, downloadable data -- but the data vendor might have issues with that.
I think I'd keep a screener as a totally separate tool and not integrated: use your favorite screening tool (of which there are many) or otherwise come up with a shortlist of stocks that you want to examine in great detail, and then use this tool.

I'm surprised I haven't found a site like this yet. But maybe one is out there.