Disclaimer Disclaimer Disclaimer! I am not an MD, but I have studied this issue for my own consideration of getting it done years ago (I haven't since I figured my breast size was sufficient for my frame), so I have read literature by MDs and actual cosmetic surgeons. Be advised, this data is *old*, so contact your local cosmetic surgeon for all current literature and FDA facts.
There are +'s and -'s to them.
First, you get a big boost with little investment, they are indeed cheaper than they have been in years [even saline ones]. Second, if you're looking also to get a more uniform shape, implants will help there [maybe more so than they should, but hey]. And those are the only +'s can I think of.
The minus are fairly common to any implants be it for medical reasons or just cosmetic [as this inquiry relates to].
First, infections. Putting anything into your body, that your body is not very familar with will cause this. Either by your immune system attacking the implants or by bacterial infects which accrue either from insufficiently sterilized implants or your own body's bacterial culture. Luckily, anti-biotics are pretty good in handling this situation, but there are a few rare cases where extraction surgery would be necessary to save one's life.
Second, possibility of implant damage. They could get bumped the wrong way some year and then *bang* you got a flat one, maybe not literally, but the fluid will leak and you'll feel it. This too can cause infections, but very very rarely so. That means going back to the doctor to get it replaced [more surgery]. This one is not very common, even for short life span implants [less than five to ten years], but it should be noted that it can happen, it's just the nature of modern manufacturing.
Third, scars. Any surgery on your body will leave a scar or two. Some fade and become barely noticable, others are very bright and evident. There are a couple ways breast implants are put in. They can go through the side [sometimes right on the inside of the arm pits] or through the nipple. The former one tends to be less problematic since you won't lose sensitivity as you would with the latter, but I believe the former also requires the incision to go into the actual pectorial, so the implants get buried deep, which can feel funny to a patient, but it seems such implants look more natural and are smaller too. Both seem to produce similar scars in the respect of noticiability, but the arm pit one has the advantage of it being out of plain sight [it's not like everyone stares at one's arm pits on the beach and etc].
All in all, there's many other things to take into account beyond the dry textbook medical concerns [aesthetics, goals, and etc], but I thought these little facts would be useful in your assessment along with the others.
-- Brede