Yea, it's a program worth a lot of money, but if you're interested in it, think long and hard about it. Don't let the recruiters sucker you into doing something you don't really want to do.
Up front, it's worth a lot of money. You get a $20,000 signing bonus (maybe navy only, but navy def. does it) and like $1200 a month while you're in medical school (taxable income).
They also pay all 4 years tuition and books expenses. Overall you're looking at probably around $257,000 that they're giving you...even more if you factor in the cost it takes to pay back loans. Say more likely closer to $350,000 or so when it's all said and done.
Now...that's a lot of money, but...remember you'll owe 4 years to the army. Let's say you do anesthesiology and wen you finish residency you can get an anesthesiology job for $250,000 a year (not too unrealistic, may even be higher). Now, you owe 4 years to the army at military pay. I'm not positive, but in the military you'd probably be making around 90k a year as an anesthesiologist. Over 4 years, that's about a $640,000 difference, so not joining the army will actually give you almost $300,000 more in your pocket eventually. On top of that, you don't have to worry about serving tours of duty where they can pull you away from your family for up to 18 months at a time. That's a pretty big burden in my opinion unless you're a true military person and you have always wanted to serve in the military. IMHO, if you've never wanted to serve in the military but are lured by the promise of money up front, don't take it. Sure you'll struggle for a few years, but it will be worth it in the end. If you've never really wanted to be in the military, taking the scholarship is as if you're selling your soul.
Also...if by some chance you DON'T finish medical school (not unlikely considering the retention rate is rather low compared to some places), you'll owe your military time...so if you get through a year and a half, leave for whatever reason...you'll owe 2 years to the army as a regular military person...not a doctor...that is another thing to keep in mind.