You have to ask yourself a few questions like, are you going to be taking lessons?, and if so, will you want a small protable amp to take with you? Do you live somewhere where loud sound will cause trouble for the people you live with? How about your neighbors?
I have a 15 watt tube amp that is WAY too loud to unleash in my single family two story home. There is no way to get to creamy tube goodness without a visit from the boys in blue.....15 true watts. Think about that.
It is a far different story when you start playing with other musicians. You will learn about the volume war all bands must go through before they start really palying together. ie. "bass player keeps sneeking over to his amp & turning up cause he can't hear himself, while all you can hear is him!" lol.
Cnosider buying a small practice amp first and hone your chops. Then as you start really developing a style you can look for another amp to play in a band. The Marshall M5 might even work for low volume rehersal, or check out the killer Blackstar HT-5... you can do a lot with one of these and maybe even plan on buying a 4x12 cab down the line to use with one of these when playing with others. Both of these amps will give you good overall tone & I think you have a headphone out along with an mp3 input with the Blackstar. Very cool for keeping the neighbors from putting reward posters for your capture around the neighborhood.
Good Luck!