Usually, you can build at least these 2 types of decks in a card game: a deck that has a lot of tiny combos ('synergy') and a deck that has a lot of high impact cards ('power level') that do not necessarily work well together. I have always been a big fan of synergistic decks and as such I like the Plasma engine so far. However, I do believe that the game is flawed in certain ways, by making the Plasma Pokemon arguably even better than normal Pokemon AND giving them their own engine, which so far has only beneficial elements (remember that Silver Mirror is not out yet in US/EU). That's obviously not how it should work from a design perspective.
Having said that, I don't think Plasma/TDK decks are really all that dominant. They show a good amount of solid results in the past few weeks' tournaments, but it's definitely not an unbeatable deck. Other top tier decks are just as likely to win a tournament as BDK, which leads me to believe that its matchups are reasonable against the field, but rarely insanely good.
I think the only potentially 'broken' card in the deck would have to be Kyurem. Turn 1 spread + turn 2 120 (with bonus damage from Deoxys) is already pretty real and should take some prizes pretty handily. And then there's more upsides: he has a rare weakness, an excellent type vs. the ever popular Landorus decks and he's not even worth 2 prizes to boot. The fact that he is nearly undonkable is just icing.
For a large tournament, sure, I would probably recommend TDK, but I wouldn't be surprised to see other decks take it home either. The meta is still somewhat varied, although the printings of Laser and the other Plasma cards seem to favour undonkable decks over donkable ones. Getting donked is extremely likely now, so fans of Blastoise/Eels decks are probably going to enjoy some very long lunch breaks this season.
tl;dr it's a good deck, maybe a little better than other decks because there's no real counter yet, but it's definitely beatable.