I will jump in as there is a lot of misinformation here. I design and teach the PMP exam at a college REP and am asked to teach at other places as a casual consultant. I also teach a certification course (local not PMP) and applied and beginner courses for project management as night and weekend classes, and in my spare time. I used to work in a PMO and was a project management consultant in my regular day job. I have coach and taught us over a thousand students. I am happy to answer questions for project management and the PMP as I am up to date more than people who wrote years ago, as I am starting to prepare for the next PMBOK6 changes.
The value of a PMP for engineers (or non engineers) is worth it under some circumstances. I would say usually about 50 - 60% of my students are engineers. I find that engineers that want to be more in the project management aspect or managerial aspect are the ones it will help. I have a some close friends who are great engineers but hate dealing with people, and don't want to manage them, they prefer technicals specks, a PMP will not help them UNLESS they play to move companies.
A PMP does NOT mean they are good project managers. What it does say is that they have the experience (4500 hours with a university degree leading projects or aspects of). And they have written a well accepted framework for Project management. They should understand what, when, and how to use the tools. Whether they use the tools properly or not is outside of PMIs control. I use the analog, one has to get a MD to be certified to practice being a dr. That certication means that they have the knowledge to be a dr, it doesn't mean they will be a good dr. Same idea here.
Project management(PM) is a different practice than engineering, (Or IT, construction), etc). It is a softer science. This what ALOT of my engineers have challenges with. Being an engineer does not give them much of an advantage, in fact many engineers are more linear, detailed, and logical which is great for engineering, but it's hard for the PMP. There are certain personalities types that will that will struggle more on the exam, I can usually have a pretty good idea on who will have problems, and who will struggle, and who will not pass. It's not all engineers, but it is usually them that do complain about the exam is not being logical. The exam is actually fairly logical, BUT in the way that PMI views it. Which is not necessarily reflective of how project are run for some people real life. ITa the PMI isms that must be learned and understood. Its understanding the PMIism its hard to pass the exam.
People, especially engineers who try and u derstanding it one their own, find it frustrating and quite frankly it makes no sense why in the world would PMI do that. In fact, I learned the PMIisms to pass the exam, however did not truly understand until years later on how, why, when, where, they are applied. I can totally understand why people (not just engineers hate it). One can learn the the PMI way of thinking just by taking test, which is one part of the recommended strategies, but they will never get the full understanding. Which if you are not a PM practioner, who cares. I actullay love Project management and use it all the time, so it was fitting that I ended up teaching it.
So my thought is, if your is company is willing to pay, and you are willing to work, there is study time involved, then go for it. I will post more on studying and tips if you are interested.