It's a tool kit, and you can use as much or as little as you want of it - run nothing but 'pure T5' or just a bit to add spice to your favourite rules set.
Some people on the board say it's the very bee's knees. Other call it opaque and unfriendly. Acclaim has not been unanimous.
In the great big book, only a few pages have anything to do with setting, and just in a general overview way. There have been hints of a "Galaxiad" here and there that advances the timeline, but there's only one of Marc, and he's got a few irons in the fire.
Yes, the latest version in PDF has had errata incorporated - given the numbers of readers and the years involved, one might argue that the older versions have had more eyeballs on them for longer and therefore would be more complete.
If you're a Traveller fan from years back, and have other rules sets, I guess you'd have to ask yourself if you're finding anything lacking in them. "Ease of use" is subjective enough that I couldn't give a thumbs up or down for how you'd find it.
I discovered Traveller in the MegaTraveller version - I found generating characters a bit easier in MT than in T5, but I haven't gone through every possible category in T5 yet.
