Talking is always better than fighting. Talking with an honest broker is preferable. Talking for the sake of talking, while the other side continues to advance their programs and the potential threat continues to grow, however, is not preferable.
At this point, it's difficult to understand why they would need more time, or why we would give it to them. Either they plan on complying with the will of the word's nations, or they do not. If not, then giving them more time is as exercise in futility and at the very least, crippling international sanctions should be reinstated. If, however, they have given us proof that they are dismantling and/or reducing their enrichment program to the level needed only for medical use and their long range missile program has been halted, then an extension of time may be acceptable if it is to allow them to get their own hardliners on board.
I've seen no evidence that they have reduced their enrichment program, or halted their long range missile program. I may be wrong, but I haven't seen it.