I think Pimsleur is great.
Pros:
It's broken down in easy, graded lessons. Half hour per day. Plus, it relies 75% on making you turn English into the new lanugage, and 25% on comprehension. Many other programs focus on vocabulary. I find other language to English vocabulary drilling almost useless. It gets too easy.
It also incorporates reviews into lessons. So you never have to go back once you pass a lesson.
Cons:
It's not cheap. (no language programs are) So, I bought my sets from lingoshop (online) as I found their prices were the best. You can return your sets to them. Or, if you ebay, I found they resell really well.
Pro or Con: (depending on your needs)
It's almost all tapes, so it won't help with reading and writing, but if you are an aural learner, it's just fantastic.
Plus, it's not very vocabulary rich You'll end up with about 500 words at the end. What it is, is grammar rich. So you'll be able to construct very sophisitacted sentences, and then you can standarize what vocabulary you learn later. (Like concentraing on medical vocabulary).