Well
James Randi and others have called him a fraud, and Uri has lost all his lawsuits against them. If memory serves, he sued Randi in multiple countries and Randi had to hand out the hat to fellow skeptics and scientists to help fund the numerous cases.
His powers can be scientifically substantiated. The JREF has a
million dollar prize for anyone who can demonstrate their powers in a proper and controlled test. No one has ever passed it, and surprisingly few people take it - that includes Uri. If he does have powers then why dosen't he take the opportunity to prove they are real? It would revolutionise humanity and open new avenues for science to explore.
This is a good site on Uri and has links to details of some of his lawsuits and claims. Interestingly this site says that Uri claimed he can't turn his power on and off. Maybe he's now found a way