Personally, I think pretty much all of the pieces of "art" which have been displayed have been crap. I just wish that people would decide for once and for all who the fourth plinth should be used for, and put a statue there.
Look at the previous occupants of the fourth plinth. "Homo Ecco" was just a statue of a bloke - completely unremarkable. "Regardless of history" looked like a dead tarred tree which had been dug up and dumped there. "Monument" was just a mirror image of the base in clear plastic - so boring. And this "Alison Lapper preganant" bores me too. As for the next bit of work... coloured scaffolding made out of meccano by a ten year old.
If people want to see artwork, they can go to one of the many museums in the capital. Much of the "art" I've seen by modern artists is dull, insipid crud that pseudo-intellectuals adore because it "challenges them"... I've seen more challenging work done by my Jack Russell cross in the back garden. So much of it just looks like the artist is taking the wee-wee and cobbled it together the morning after an all-night pub crawl, just minutes before the exhibition.
The other three plinths are occupied by statues of people who made significant contribution to Britain's history. Why not get a statue of someone important to put on the fourth plinth. Put it to a national vote, stick the statue there and let's move on to sort out some of the more important issues that face us these days.