Crest Whitening Strips Review

We've been trying out Crest Whitening strips for few years now for tooth whitening.  The product is a great deal and convenience at under $30, but has several challenges:

1.)  You need to use it twice a day for 30 minutes to whiten your teeth for a week.  It's comparable to other dental products for tooth whitening -- but the twice a day factor makes it a challenge. 

2.)  The strips only whiten your front teeth.  It leaves no change to your back teeth and molars.  It's a good value - but anyone looking closely can see a stark contract in the tooth color. The uneven whitening makes it a questionable deal - but is a good way to try out / experiment with tooth whitening without having to see (and pay) your dentist.

In summary - for around $30 - Crest Whitening Strips are a clever product to try out tooth whitening.  The time commitment and uneven whitening can be drawbacks but its a good way to start out.  What do you think?  Have you tried these?