i got probably the same one you are looking at on amazon...
http://www.amazon.com/Philips-HX5610...words=sonicare
i went to the dentist a few weeks ago and i too was recommended to get one. i had braces on my teeth when i was a kid and the middle part of my bottom has moved back quite a bit because i didn't wear a retainer after long. and it has caused a lot of congestion down there. they were telling me that i could really benefit from one because a normal brush won't be able to clean down in that area as well as an electric tooth brush would be.
they also recommended to just get the cheapest sonicare one that i found because the higher end models brush the same but have extra features that don't really make a difference in the brushing. and after reading about the differences, i concluded the same.
the model i have is on for 2 minutes, which is the recommended time to brush. it will turn off after 2 minutes on it's own, or you can push the button to turn it off yourself.
the next up model had some mode where it beeps every 30 seconds, since you are supposed to brush 30 seconds on each side of your teeth - front bottom, front top, rear botom, rear top.
the next up model i think had a "whitening" feature, which all that did was go for 2:30 instead of 2 minutes. again, something you could do with the lower model. the higher models also look sleeker, but it's a freaking toothbrush.
since i've gotten it i have definitely noticed i have fresher breath. i also have noticed that i definitely did NOT brush my teeth for a full 2 minutes prior. probably closer to 1 minute. but now i always go until it turns off on it's own.
it took some getting used to the vibrations on my front rear middle tooth area. it tickled a bit the first few times, but now i don't notice it at all. i also brush my teeth with my mouth full closed now because i don't have to manually brush it like i did before, and i've noticed a lot less "mess/splash" around my sink area.
i bought one for my wife at the same time and we're both really happy with them.