It's kind of hard to say who has gotten the better end of this deal so far.
On the Brewers side, Kevin Mench has basically been a disappointment batting only .229 since joining the Brewers. He remains mired in his power slump having hit only 1 homerun in 83 AB's with Milwaukee and just 13 RBI. He hit his 1st homerun as a Brewer on July 30th against the Reds and has not homered since.
Laynce Nix has not had much of a chance but has done fairly in what little action he has seen. In 27 AB's Nix has 1 double, 5 RBI and is batting .286. A big improvement over his .118 BA in 32 AB's as a Ranger this year.
Francisco Cordero has been the biggest pickup for the Brewers by far. He has been totally lights out going 1-0 with 10 saves in 10 opportunities and has not allowed a run in 12.2 innings with Milwaukee while striking out 14.
On the Rangers side, Carlos Lee has done a very nice job mostly in the 3 spot for Texas. Despite the power numbers not being there, only 4 homeruns in 134 AB's after hitting 28 homerun in Milwaukee, he is batting .321 with 13 doubles and 26 runs scored in 33 games.
Nelson Cruz has also showed a bit of potential hitting 2 homeruns with 7 RBI in 36 AB's with Texas, although he is only hitting .139 and has struck out 13 times.
Both teams have gotten 1 big producer out of the deal and both teams are also basically out of the playoff race. I still maintain that if the Rangers can resign Carlos Lee they will have gotten the better end of the deal, but the Brewers still have a lot of untapped potential in Mench and Nix. Unfortunately the change of scenery doesn't seem to have helped Mench any.