As expected, the first shoot down of a medium range (by local standards) missile over Tel Aviv was widely (sometimes wildly) celebrated. I don't mean to rain on the parade, but i still see this as the first successful shoot down of a mid-range missile by any of Israel's defence systems. I'm sure the military "experts" here will be indignant that I'm the one to point that out, but I consider it pointing out the obvious, subject to corrections of course.
Based on my scan of print media, and being very conservative with the numbers (i.e. 3 instead of 5 missiles in Tel Aviv), the total Mid-range missiles fired on Tel Aviv and Jerusalem so far were 2 on Jerusalem and 3 on Tel Aviv, with one shoot down (If anyone has different, but verifiable, numbers please feel free to correct me). (1,2,3)
Based on these preliminary numbers, the shoot down rate is one in five, in other words a 20% success rate against Mid-range missiles; This is by any of Israel's missile defence systems, and not just Iron dome.
If and when war breaks out between Israel and Iran, Israel will not be facing a short range missile issue from Iran, but rather a mid-range, and long range missiles, including ones from Hezbollah.
We'll probably hear and read more about this once the likely Egyptian cease fire becomes a reality, and the "circle the wagons" mode gives way to post-war objective analysis. If the Israeli military concludes that the defence system(s) are not ready to face the Iranian (longer range) missiles then that should make an imminent attack against Iran less likely, and that should be of interest to many. Keep in mind that at least one new system is reported to become operational no sooner than 2014 (see article below).
Below is a link to an AP article posted by the NY Times about the Iron dome system. It provides good general information and background. Again, military "experts" here must forgive the lack of details, I'm sure the writer didn't intend it for the generals who frequent this site.
(3) see above video (it shows two missiles, one hit, one shoot down).