According to Tom Singer of MLB.com it ranks 4th in the majors:
4. Brewers: How can a team let a 44-save closer (Cordero) and a valued middle man (Linebrink) walk, yet still rate a top-notch bullpen? Milwaukee GM Doug Melvin scores on the proactive meter.
Cordero already had a track record (with Texas) for crash-landing after a big season, so Melvin felt better about rebuilding his bullpen and went all out. A lot rides on whether Guillermo Mota and Eric Gagne can re-enact the deadly combination they formed with the 2002-04 Dodgers.
There are people with closing experience all over the place. Melvin also added David Riske and Salomon Torres, and Derrick Turnbow is still on the scene. Brian Shouse has aged into a trusted matchup lefty (only 24 of the 94 he faced reached base).
If you see Mr. Singer you are advised to immediately flee as fast as you can in the opposite direction as he has clearly lost his mind. I like this the best: "There are people with closing experience all over the place." Yeah, you know, guys like Dan Kolb.
In all honesty, I think the bullpen will be alright. Bullpens are hard to predict because the lifespan of a relief pitcher, especially a closer, is pretty short. But I don't think there's much chance that it'll be the 4th best in baseball. Maybe the 4th most recognizable.