I used this for six weeks only, haven't had to even change eh brush head, and it started to make some weird noise after a month. Now the vibration is almost gone, just noisy. I bought this as a respected Japanese model backed by the known high Japanese standards, however, It seems that it is actually worse than the cheap ones I could buy somewhere else.
Update: After contacting Philips for warranty coverage, they asked me to go unperson to their service center in Saitama and have it repaired after 1 to 2 weeks. It basically going to cost me 2.5 hours of travel plus 4000 yen of train fees, in addition to the waiting time.
Save your money and buy a cheaper one from other sources, rather than worrying about Philips ridiculous warranty.