Well, I didn't look up the failure rate for IVF, but there is one, otherwise, why select multiple ovum from every each woman (other than prior to surgical removal of the ovaries). When Dolly was first cloned, the success rate was horrible, less than 1% viability. Currently, complex mammals are cloned at a success rate of around 70-80%. The main problem seems to be issues with the epigenetics of somatic nuclei being implanted in the ovum. This results in abnormal development, which would be pretty horrific in the case of humans (for no real benefit, IMHO).
I think, as has been mentioned here already, the development of induced pluripotent stems cells is the most favorable field of study due to it's impact on regenerative medicine. Need a kidney, grow one, same for a liver or a heart or a lung. These would definitely be life extending and quality of life advancements. I'm 100% on board with this sort of research.
I've follow this stuff on and off for years, but the basics can be found on Wikipedia for those who want more background and that's where I grabbed a couple of statistics. I'm not a geneticist or a bioethicist, but I'm not in favor of an undisciplined approach to science that has no collective ethical governance that reign in study to the most needful advances that do the least harm. We are already doing genetic screening of embryos, the obvious next step is genetic modification (already done in china) - but this science is so complex and has so much potential to change what, in fact, a human is - that we need to decades of research on the long term effects in less complex organism before we venture forward. That, and advancements if computational power and techniques will allow simulations that greatly expand our understanding without harm or risk to a single organism.
Going back to human cloning, the fundamental problem for me is why. Just because something can be done, doesn't mean it is reasonable to do so. I see absolutely no reasonable need for it.