Play it, and like it.
1. Chargen. Random (or semi-random) prior history was the defining feature of CT, but it quickly became confusing and was totally biased toward the military. MGT fixes this while keeping the initial simplicity of CT, and adds the flexible and adaptable Events which are insanely useful, especially to a Ref. I'd now say Events make the character, not the skills.
2. The Task system. Possibly a minor development, but the linked task rules combined with Effect are really useful. Makes it possible, with some preparation, to grade non-numerical successes. Such as, when questioning an informant, you can list increasingly useful responses based on Effect. (E0 - tells you Bill lives in the starport. E1 - Bill lives at the starport, and likes country & western. E2 - Bill often goes to Smoky Joe's Cowboy bar, etc).
3. The Combat System. Yes, I really do!
It's simple and streamlined, compared to other rpgs or even previous versions of Traveller. Not perfect, but I've already sorted some minimal house rules for armour piercing, for instance. And while I initially thought armour values were too low, through over a dozen extended combats I now find them pretty much a good balance.
4. New equipment. Fixing the room-sized compuer issue, simple but effective rules for augments.
5. Small craft rules. Making fighters finally viable.
6. Some more 'realistic' options for worldgen.
7. A wide variety of careers to choose from.
8. Productivity. Over 10 books released in just over a year. That's rapid by any measure!
Of course, that brings up the major downside, which is the varying quality of proofreading. Some rules could be more clearly explained (barrage attacks, for example), and some descriptions could have been better. However, the excellent return offer somewhat makes up for it. Not sent my Mercenary or High Guard in yet, as I've been getting good use out of them, but Agent and Scoundrel appear soon and they're what I've been waiting for.
So that's the positive.
Now to the negative. I'll certainly give that a lot of the stuff on 'the other' thread could be described as constructive criticism, but a lot of it also amounted to little more than rehashed bashing of the unfortunately described magrail guns. While Bill might be fierce in defence of his views, I admit that he has been, on the whole, polite and courteous. The same cannot be said for another of the 'critics', and while I've tried to avoid getting involved here on COTI in pointless debates sometimes the invective deserves a response, if only to make clear to any newbies that these views are only one POV among many.