To answer you properly, lets review the state of T5
Character Generation - It works, it is missing some details as per higher education examples etc, but, it works. The characters generated are not comparable to the earilier editions with the way skills, knowledges and attributes work out, but, hey, every version of traveller needed a method of converting characters so that is a moot point.
World Generation - It is compatible with what has been in the past, but has alot more added onto it. I would have liked biomass/biocomplexity/biodiversity values that affected trade as well as creatures, but, that is a nitpik and not a problem for most.
Equipment - QREBS and the various builders all cover equipment and other than more solid designs being available, it is a working system.
Same goes for starships, genetics, even psi. Everything has been solidly built and although it may be more abstract than earlier math heavy versions, it is consistent and solid.
BUT intertwined through characters, equipment, worlds, trade etc are assumptions that are based upon the task system. The task system is broken. That has been shown from both a mathematical as well as a user preference standpoint.
So, although it is close, the broken task system makes the rest of the system broken.
T5 has built itself on a foundation of loose sand.
So, to answer your question, no, the system is not playable enjoyably as written.
If you have a group of traveller players, or old school role players, you can adapt and house rule with the experienced players making allowances for the system.
But, put the system in front of totally new players, even if it is in a format that is better laid out, such as the T4 books. You will find the system does not encourage new players and that the old players will have the T5 book in their collection gathering dust.
Buckets of dice systems never become overwhelming successes - TnT, the first buckets of dice system is a testament to that and it is far easier to learn/play than Traveller is.
Roll under systems only appeal to players who have encountered the concept in other roll over systems. Even then, they are not the most popular games, regardless of how good and efficient the game mechanics are. BRP/Runequest/COC is a perfect example of popular roll-under systems that still do not sell as well as Roll over systems, while the number of roll under percentile systems that have been lost and forgotten over the years seems beyond number.
Attribute Pip=Skill Pip is a new one on me. Most systems make skills far more important than attributes on a value for value basis, but even the this is hard rule only adds one die to the roll regardless of how outclassed the characters skill level is. Hasty tasks have the same sort of impact. If you add a die per die the skill is exceeded by, only makes it more likely to succeed (more dice = higher chance of success).
I have been experimenting with task difficulties being numbers instead of descriptive words ie instead of automatic, easy, average, hard etc, I use level 0 task, level 1 task etc.
Each level of a task represents the number you need to beat based upon core attribute+flux.
The target number is difficulty level * 5 so, 0, 5, 10, 15, 20, 25 etc.
Skills lower the difficulty level on a 1:1 basis
Equipment gives a bonus based upon its min:max skill ie, if the equipment is skill 0:4 then you get a +1 to your flux roll for every skill point to a maximum of 4. If the minimum skill is higher than your skill level, you don't know how to use it. Equipment can have a further modifier to the flux roll depending upon quality, computer assistance etc.
Modifiers make the level higher/lower etc and there is no reason to tell the player the final target number, just ask them to roll and give the result. Modifiers could adjust the difficulty level or act as a flux modifier.
Extraordinary Success is a natural flux of 5 while critical failure is a natural flux of -5.
You can not have a Extraordinary success if the difficulty number is greater than your skill, while you can not have a critical failure if your difficulty number is less than your skill.
Opposed tests have the target number of your opponents roll.
People assisting with a task get a reduced benefit ie 2nd person lowers the difficulty by one for every 2 levels of skill. The 3rd person lowers the difficulty by 1 for every 3 levels etc.
So, T5 flux mechanic. No buckets of dice, similar to roll high. Attributes are important but skills are more important. No upper or lower limit on difficulty levels.
It is far from perfect, but it is something I came up with in about 10 minutes.
It is simpler than T5 and can handle the same range of things.
I am sure that the players on this list could come up with something better and have it work with everything else in T5.