For home use/recording it's great. Jimmy page used little amps on the early Zep albums and it sounded huge (Josh Homme, too). Also, if you have neighbors very close to your home, it will annoy them a little less. On stage, a PA would make having the lower wattage a non-issue. The sound pressure matters most if you want the speaker cones to distort or a certain response from the cabinet. If you have a cabinet that resonates a lot with a large amp, it will resonate less and the speakers will not distort until pushed harder.
Keep in mind: a 100W master volume amp with a logarithmic volume pot set to noon is only putting out a maximum of around 10W and that's if the channel volume is maxed. A 25W amp will produce a similar response somewhere between 4 o'clock and 5 o'clock, but the headroom is more or less gone. If you don't play very clean, you use your guitar volume a lot, or you want to hear the power amp distorting, the 25W will be fine for very, very loud playing. If you keep your master volume lower than noon on a larger amp, the 25W will present few issues.