Its a little worse than the other free blue counterspells, just because it requires a board presence from you before you can cast it for free, as opposed to Force of Will and Pact of Negation
If a permanent with an ability that triggers "at the beginning of the end step" enters during your first end step, that ability won't trigger during that end step, but it will trigger during your second end step
Slivers are an excellent tribe in Commander, have a playable Pauper deck, and even have some fringe Modern combo decks
With cards like these, Braids becomes an incredibly efficient card draw engine that is always available from the Command Zone
Some people say it's Ulalek, Fused AtrocityUlalek, Fused Atrocity, and some people say it's Azlask, the Swelling ScourgeAzlask, the Swelling Scourge