Since no one has made a detailed reply, Ill try to give it a shot. I graduated from FLETC a month ago (US Customs) and had several former BP guys in my class. I also did an exercise with the BP last January (USMC training).
I wish I had good news to tell you, but most BP agents and former agents I talked to, were not happy with the job. Training is probably the most structured of all federal law enforcement agencies, ie, march to class and live like you're in boot camp. It is a long academy mostly because you have to learn some Spanish. My classmates said that the academy was just an ordeal.
Life after is not much better from what I was told. Expect to go to the southwest border. If you like McAllen, TX or Naco, AZ, etc, you will love it, but don't expect Key West or San Diego as a first assignment. Pay is on par with other Federal LEO positions, plus you will work 8 hours overtime each week, mandatory (this is from an agent in AZ). Incompetence seems to run rampant within the organization. (Just read the news and you will see how bad INS as a whole needs help). It is not to say there are not good people out there, but many, many of them leave for other agencies. (There has been a mass exodus from BP). Promotion is stagnant.
If you are going to use this for an entry into the federal system, I would suggest Customs Inspector and try to transition to an agent later (It doesn't matter if you want to go to a different agency). Most inspectors seem to like their job even if they transition.
If you want to go into Law Enforcement, there are a lot of State and Local agencies that are high quality seeking applicants. Pay will be similar at first. If you want Fed, then you can still apply in a couple of years. But as a local guy I imagine you will see a lot more action. A couple of Special Agents I know who were locals really miss it. Good luck.
Stray