The deck box is, as others have said, pretty useless. Between the fact that it is extremely flimsy and that it can't hold a sleeved deck, I can't imagine I would use it when I can store more in the slightly more durable prerelease deck boxes. That being said, the design does look very good.
I don't really use the damage counter dice, simply because I like the dice I have much better, and I have 36 of them. I would recommend making them in colors slightly less bold, so their colors don't clash with the cards' as much. The flip die is neat, but my states dice, regionals dice, and pokegym dice are much, much better looking in my opinion. For me to put one of the ETB flip dice in my dice bag for use, I would make it a nice color with pips of a different color (like a light blue die with gold pips, or a purple die with orange pips). The set logo is pretty cool, but I think I would prefer it being a tad smaller.
The box holds cards well, except for the minor things people have pointed out above.
The condition markers are very nice, but I feel like they would be redundant if people are getting multiple ETBs or getting them each set, because who really needs 6 burn or poison markers? I gave mine away, as I already have fantastic markers, so this judgement is from seeing them used rather than me using them myself. It's very nice to see easily accessible, high quality condition markers, however. I might keep my next ones.
Having all the basic energy is a great move, making it easy for people without them to get enough without picking apart theme decks. However, the box is advertised to more competitive players, so I don't think they're entirely needed. If there was a seperate product with, say, 5 holographic energies of each type with unique artwork (like the CoL ones had) every other year or something, people would love to buy them.
I think the Elite Trainer Box is a fantastic product. The one I have was given to me, but I plan to buy one of the plasma blast ETBs mainly for the sleeves, even though I already have everything I need from the set pre ordered. I feel like if the deck boxes were upgraded to plastic with a velcro flap, there were sleeves, maybe 5 packs, and dice, I would buy one every time.