Israel has a coalition government where lots of small parties work together.
The problem with these types of governments is that it becomes easier for extremist nutters to get a say in how to run the country.
Systems like first past the post or the electoral college are supposed to make it harder for fringe parties to gain power.
Or, in the case of the UK where it is a straight FPTP system, it allows a government which would cause "dismay" in the majority of the public take power. A few votes here and there and the Tories could have taken an outright majority.
Isreal's political climate really can't be compared to the UK, a majority progressive nation.
ETA: I really think PR would deflate the BNP. We might get a few MPs from them initially, but I think most would gravitate to UKIP. A modified FPTP with the rankings might give more power to the fringe whilst diluting the power of Labour and the Tories.
ETA2: And what else the FPTP gives us are things like the expense scandal, pandering to populist or right wing sentiment and banking by Labour, and a bit of a swing to the left by the Tories, at least in their public image. And, to be honest, pandering to the right by the Lib Dems particularly on the issue of immigration.
After 2000, I don't hold the US up as a paradigm of representative democracy, but that doesn't change the fact I can see huge flaws in a non-American system.