Fine. What about a cloudy day? Or maybe a shadow or indoor area that needs to be shot? Sunny 16 isn't going to work.
I use an iPod Touch with an app called MyLightmeter. It has a nifty looking UI and is a nice package. I can use my Android phone to do the same but prefer not to. Once you have it on the whole day, the battery will drain and you're left without a means of communication. I find it much safer to use an external meter to address this sort of problems.
Then you have the physical light meters which are great too. I have four. One hand held Seknonic, one old Kodak meter from the 1960s, a new Voigtlander meter and the dedicated Pen F clip on meter.
The Pen-F is a CDS meter, requiring a battery and it is not as accurate as the built-in meter in the Pen-FT. I had to test the accuracy to know how far it was off before using it. Using the readings from the Voightlander, I found out that the clip on meter was one stop under. Phew, that was a relief as I can easily compensate for this by dialing in a higher ASA for the meter.
By calibrating the meter to ASA 200 when using ASA100 film, you are essentially compensating for the lost of 1 stop. This also means that the meter will not be just a display piece but a working meter which you can use in actual photography.