It is easy to criticise the WTO based on high profile stories but the WTO, and it's predessor the GATT, has done a lot of good for the global economy since its inception (GATT - 1947, WTO - 1995).
The GATT was set up with the objective of "to promote international trade by lowering 3 main barriers to trade (tariffs, export subsidies, domestic support)". In that sense it has done just that. It is estimated that 97% of international trade is represented by the WTO through it's 153 members. Tariffs have estimated to have decreased from 40% to 5%. And that 9/10 disputes have been settled constructively.
But it has been argued that the 9/10 disputes that have been settled are "easy" disputes and that the tariffs that are remaining are on the crucial industries that would really make a difference, such as food and automobiles.
The latest rounds of talks, the Doha Development Round was initiated in 2001 and has repeatedly stalled. The main points of contention have been agriculture subsidies to the US and EU, which developing countries want reduced. Lower prices in developed countries have increased imports in developing countries where local farmers have been impact.
On the other side, US and EU have blamed China and India for being overprotective and not opening up their markets to industries such as food and automobiles.
The WTO has also been widely publicised for failing to settle the dispute between Airbus and Boeing in the commercial aviation sector. Airbus being accused of receiving "launch aid" from EU governments, which loans to Airbus with effectively zero interest rates. Boeing being accused of receiving hidden subsidies through development contracts. Both have been found guilty by the WTO last year, but the situation is far from resolved as appeals and counter-arguments will make sure that this dispute will not end soon.
(in my opinion, it is in the best interest for Boeing and Airbus to resolve this dispute swiftly. They face increased competition from Bombadier and COMAC who have recently announced an agreement to work together.)
(Also COMAC is a state-owned company, while the state also owns several banks. therefore it is likely that COMAC will be funded via the government as well. I think the best thing to do would be to agree on a interest rate for government loan to have transparency on the matter)
The rise of regional trade agreements, which seem to be a lot more dispute free than multi-lateral agreements. RTAs are agreed on more frequently and can be tailored to suit those countries involved. Trade agreements between trade blocs can be made to other countries, which was the case with ASEAN making trade agreements with India and China respectively at the start of 2010.
While there have been some high profile disputes, and the ongoing stalling of the Doha Round, I do think the WTO is a beneficial organisation. The theory of Free trade is a positive one, as it does stimulate economic growth and is beneficial to consumers. Not only does it help economic factors but it also helps politically, as it promotes peace. As such i think the future of the WTO is fairly certain. However the future of the Doha Round is probably less so. Having gone 10 years without any substantial breakthrough in the dispute over agricultural subsidies, i think the WTO may have to say that the targets were ambitious and come to a compromise so that the round can end and they discuss other disputes. I don't think the credibility of the WTO will suffer as a result.