I have found it to be extremely worth it, to the point that I don't like to fly un-engineered ships anymore, they are just too inferior.
Even in my brand new game, which I started just after 2.2 dropped, as soon as I got my first Cobra, and kitted it out with an A-rated frameshift drive, the next thing I did was unlock Felicity and boost my jump range. It made doing rares runs really nice.
I've spent umpteen hours engineering my ships, and I have a few (Corvette, Cutter, Anaconda, Python, Asp Ex, T6, iCourier, iEagle, Cobra MkIII) because I love how amazing they become. I'm not even done with them all, but I'm happy with them now, and working on more.
Yes, it's time consuming. Some of it is quite tedious, although tedium doesn't seem to bother me as much as some folks, as long as the resulting reward is good enough. And it is.