That's the line being taken by the UK media, of course every election is presented as a "once in a lifetime" chance, when it rarely ever is.
What is deemed exciting is that the polls for the past few years have indicated that neither major party is likely to win a majority of seats. There are two reasons for that.
Firstly, boundary changes that were recommended by the Electoral Commission, but which perversely need Parliamentary approval to be implemented, have not been. This is largely because the current boundaries tend to favour Labour and the Liberal Democrats, because both parties have constituencies that have proportionally fewer voters than the ones currently held by the Conservatives. So some MPs represent fewer voters, meaning their votes count proportionally more than those in others. The Liberal Democrats refused to support the boundary changes in coalition, so for the Conservatives to win a majority of seats, the party needs, on average a 4-5% higher share of the overall vote than Labour, which would (notwithstanding the next point) have more seats than the Conservatives, even if the Conservatives had a higher proportion of the vote. Remember, this is still the vagaries of First Past the Post (and voters rejected a mild form of electoral reform in a 2011 referendum).
Secondly, minor parties are making a significant impact, in varying ways. Not the Liberal Democrats, who expect to get hit because a fair proportion of its voters didn't agree with it backing the Conservatives and may feel lucky to win half the current lot of seats. UKIP is taking support from the Conservatives in the south, but also Labour in the north (it is polling a strong second in many traditional "safe" Labour seats, primarily because of immigration-phobia, but also perceptions that Labour is a party of the so-called "metropolitan elite". It will be pleased to get at least 3 seats. The Greens are having a small impact too, mainly taking some Liberal Democrat voters (as the Liberal Democrats were the green evangelists of the past) and Labour ones, although the Green run Brighton Council's disasters and the shockingly poor performance of Australian born (yes I don't know why Australian Greens migrate to pollute the planet with their ideas) leader Natalie Bennett. It will be surprising if it wins more than the one it has at present.
Yet none of those parties is having the impact of one that has a much smaller percentage of the UK wide vote, but which could win more seats than the Liberal Democrats, UKIP and the Greens combined. It is the Scottish National Party. Fresh from losing the independence referendum, it has rallied the 45% support that the independence idea gained into direct electoral support. It is eviscerating both Labour and the Liberal Democrats in Scotland, and is looking like winning most seats there. By wiping 30-40 seats from Labour's tally of "safe seats", it looks highly unlikely that Labour could win a majority.
So, the most likely outcomes of the election are for the largest party to try to cobble together a coalition or series of confidence and supply agreements, with one, two or even more parties, and to fail and find the second largest tries the same.
From a psephological point of view it is interesting. The Conservatives could pair with the Liberal Democrats again, and possibly UKIP, and the Democratic Unionist Party (DUP) of Northern Ireland might back the Conservatives, perhaps the Alliance Party could too. However, the Greens, SNP, Plaid Cymru and the SDLP (from Northern Ireland) have all indicated they would "block" a Conservative government, and so might back Labour. The Liberal Democrats have said the largest party in Parliament is the one it would most likely work with, but UKIP is highly unlikely to go with Labour. The DUP hasn't ruled out supporting Labour as long as Northern Ireland got its pound of pork. Meanwhile, Sinn Fein wont take up its seats, although there have been rumours of Labour-Sinn Fein discussions.
My suspicion is that there will be another election later this year.
However, in terms of the variety of what is on offer, it is more nomenclature than substance, as I will write about shortly.