I really like the approach to standards of different vendors contributing tests to a constantly-growing test suite. It seems much more robust and less game-able than the existing standards & performance tests, like Acid and Sunspider. It's a shame that both this, and the WC3 HTML5 tests, seem to be dominated by Microsoft, but I think Microsoft is making the right decision by contributing a ton of tests and I can't fault them for other vendors not doing the same.
The reason I like this competitive, evolving style of tests is simple: it's much harder to design a browser to the test, rather than the standard. With, say, the Acid test, browsers build in the specific functionality that it tests, which results is very un-even standards compliance and altogether mis-representative test results. If it's not on the test, vendors drag their feet on implementing. With this new style, if there's any part of the standard that browsers haven't implemented, one vendor can implement it, and contribute tests around it. Now they can show how they're more standards-compliant, and everyone else will catch up because they're being tested on it. This competition encourages all the vendors to a) implement the full breadth of the standard b) contribute tests cover the full breadth of the standard. Win-win for users.
Its Microsoft, but I'm still happy about it. Always a good thing to have a test like this. Hopefully very soon the numbers will be 100% across the board.
The reason I like this competitive, evolving style of tests is simple: it's much harder to design a browser to the test, rather than the standard. With, say, the Acid test, browsers build in the specific functionality that it tests, which results is very un-even standards compliance and altogether mis-representative test results. If it's not on the test, vendors drag their feet on implementing. With this new style, if there's any part of the standard that browsers haven't implemented, one vendor can implement it, and contribute tests around it. Now they can show how they're more standards-compliant, and everyone else will catch up because they're being tested on it. This competition encourages all the vendors to a) implement the full breadth of the standard b) contribute tests cover the full breadth of the standard. Win-win for users.