I know alot of people with Sonicares, I've had them since they came out 4-5 years ago. All the people at my dentist use them (and sell them at cost which is $55-ish), most of my coworkers have them, all of my family have them. Not one has regreted it. Even some really cheap bastids at work, who wont spring for a birthday card for their own mother (true), found the sonicare to be a great deal.
first off, the 'sonic' part foams your toothpaste and actually makes the toothpaste work 10x better. it massages your gums (good) and actually removes tartar in places you cant reach easily. You only have to use it on the front of your teeth because the toothpaste will foam between the teeth and the sonic part works the other side of the teeth.
All I can say is that in 4 years, I havent spent more than 10 mins in a dentist chair. I go in for my 6 month checkup, there is nothing to scrape. They polish, I bust out of there.
Over the years, I've found that I really only need to use it 3x or so a week. So, I brush normally, then every few days use the sonicare to 'catch up'. works great for me. it leaves your teeth like you just left the dentist office. Trust me, you will be able to tell.
I really dont think Sonicares are anything like other electric toothbrushes. They do something you simply cant do, occilate your hand at 20000 rpm. Can you have good dental hygene without one? absolutely. But, if youre getting scraped during cleaning in the dentist chair, I think you'd love a Sonicare. If they arent finding anything to scrape, then you probably brush 10 mins a day and dont drink soda and prolly dont need a sonicare.
As far as a deal? Well, $60 can save you a TON in dental bills down the road. I paid $120 for my Sonicare (before my dentist used/sold them), and didnt regret it at all.