Traveller contains many very intriguing ideas and concepts, intellectually speaking. I had a blast marveling at the technology building rules.
But as a role-playing game, it falls utterly flat for me.
It desperately needs character, warmth, heart, engagement. I have never seen a relatively established brand of rpg with so few adventures worth the paper they're written on.
To be brutally honest, most scenarios come across as little more than a thinly veiled excuse for a wankfest trying out some subsystem (planet generation rules, plasma cannon construction rules) with next to zero thought on writing a compelling story.
Which is extra chilling given our hobby's generous definition of "compelling" where "there is goblins in a cave, go to cave, kill goblins, return with loot and XP" is considered an above average story-line... ;-)
I had a look round when I hoped to start a Traveller campaign using the starter adventure in the otherwise maligned New Era rulebook. That scenario was quite interesting. However, I found zero older scenarios worth even using as a starting point. When I realized I had to create absolutely everything except technical details myself, I moved on to another game.
I would even go as far as hesitate characterizing Traveller a complete role-playing game. It is not comparable to D&D or WFRP or Vampire or most other mainstay games. It is much more accurate to call it a toolbox for scifi worlds, with a high degree of specificity (just like D&D is only good at playing D&D like fantasy, not all kinds of fantasy).