What are the pros and cons of engineered hardwood?
Generally speaking, the only downside is that you can typically only refinish (sand down and re-stain) engineered hardwood two or three times, because there is usually between 1/32" to 3/16" (0.6 to 4.5mm) of the actual hardwood layer, and the rest is plywood, fiberboard, or another hardwood. 

You'll typically pay more for a thicker top layer, which means you're more likely to be able to refinish it more times, and more importantly, it will last longer.

Like most things though, you get what you pay for. With cheap engineered hardwood there are likely to be other problems (just like with cheap laminate or even real hardwood) including not using a good quality base, which will warp or absorb moisture, poor manufacturing quality causing the top layer to come off at the ends, or the tongue-and-groove not to fit together nicely.