We are created from hundreds of millions of years of natural selection. Those with faults die, those without faults survive. Under such a long amount of time you'd think that the best of the best were the only ones left? I believe that's true if the process wasn't pretty much random, we've gotten what a pretty good system of our bodies, but it was all made randomly and through trial and error. I see the human body as a really messy program, it works fine, lags a bit and sometimes has the occasional bug, but the code itself is so messy and incomprehensible there is no chance of really editing the body without trial and error (aka medicine).
So I think genetic engineering could be a way to clean up the code. I think genetic engineering would be good, it would give a lot more freedom to people, allow people to live longer, survive better, maybe need less food or resource? The options are near limitless and we could really start to evolve humanity in the direction we want. That said, we're talking about changing a billion years of evolution, it's not something we're going to be able to get perfectly in 50 years, there's going to be mistakes and people will become deformed or killed. Bad things will come of it, to some people, in failed tests, things that we don't really understand, we are trying to be as careful of it as possible but there is basically no chance to have a perfect flawless system. It's whether the ends justify the means, in most cases I don't think they do, but here I think they might. A few dead people to save 7 billion people from extinction due to over crowding, disease, famine and resource?
I think genetic engineering is very complex, very hard to change, but it is possible. I think that it should be done.