well, i have played some of the best decks in the HL format with the deck and the best players who used those decks.
MErcury does very well.
in the HL format, i went 5-0 at 3 city championships(lost in the finals, in either 2 or 5th place) i had bad match ups(zappy manetric and trodes, spintail, and ZRE) so i know the deck is good, but sometimes it cant overcome some of the.... trickier decks that are faster to set up.
and the jury is still out on it since alot of the stadiums merc used are no longer viable choices as HL was rotated(desert ruins, magnetic storm etc) its a decent choice... but it can definately be improved.