MobileBurn reviewed Samsung's SGH-P300 Credit Card Phone which measures only 88mm x 54mm x 9mm (3.5" x 2.1" x .35") in size, and weighs in at 83g (2.9oz). Here's an excerpt:

Sadly, it is in the most basic of phone functions that the Samsung SGH-P300 shows its only real fault of note. Call audio quality on the P300 is relatively poor. Both inbound and outbound audio quality lack clarity and suffer from differing types of distortion. My first call made on the device, with my mother, immediately resulted in her asking what device I was using. She knew right away that I was using a new phone for the call. The audio quality when using the speakerphone or a Bluetooth headset is also bad. There really is no way around it.

That is a real shame since the device does everything else so well. Battery life in two separate tests (one transmitting silence, one transmitting constant music) both resulted in over 7 hours of talk time when used with a 1900MHz GSM signal. That is more than twice what Samsung claims for the device (3 hours). When you toss the leather case onto the phone, you can expect another 50% worth of talk time. The battery performance is no doubt aided by the fact that there is a strong signal here in my office and that the device itself also exhibits good reception properties in general. Your personal results may vary - especially on the 900 and 1800MHz frequency bands that we didn't test.

The Samsung SGH-P300 does not have a real profiles system, but does at least have easy access to a configurable silent mode. Depending on how you choose to configure it, entering silent mode by long pressing # key can either make the phone 100% silent or cause it to activate the vibration alert for calls and messages. Your options for the regular mode are limited to a selection of ringtones, the option of using a "vibrate then ring", or a vibrate only setting. There is no option for "vibrate and ring" on the P300.