In the history of the NBA, there has only been 6 other times where a player has had 40+ points and 15+ assists, this includes games against s*** teams, 2+ overtime games and playoffs and its only been done twice since 1994. The last time it was done, was in 2010, by of course, Lebron.
http://www.basketball-reference.com/play-index/pgl_finder.cgi?request=1&player_id=&match=game&year_min=&year_max=&age_min=0&age_max=99&team_id=&opp_id=&is_playoffs=N&round_is_ec1=Y&round_is_ecs=Y&round_is_ecf=Y&round_is_wc1=Y&round_is_wcs=Y&round_is_wcf=Y&round_is_fin=Y&game_num_type=&game_num_min=&game_num_max=&game_month=&game_location=&game_result=&is_starter=&is_active=&is_hof=&pos_is_g=Y&pos_is_gf=Y&pos_is_f=Y&pos_is_fg=Y&pos_is_fc=Y&pos_is_c=Y&pos_is_cf=Y&c1stat=pts&c1comp=gt&c1val=40&c2stat=ast&c2comp=gt&c2val=15&c3stat=&c3comp=gt&c3val=&c4stat=&c4comp=gt&c4val=&order_by=pts
Even with two overtimes, Lebron "only" played 48 minutes and he took over the 2nd overtime, a part of the game where most players are fatigued and would be slowing down, he seemed to actually get stronger. The numbers he put up are impressive, it doesn't matter who he was playing against and how many overtimes there was, 40 point, 15+ assist games don't happen very often.