There have been many AMD processors with "A" designation. The answer to your question, ranges from "OK" to "I wouldn't buy that today". Without a better description of the model of PC or processor, and a budget, there is no specific answer.
I'm intron purchasing a desk top computer with AMD I4 processor. Is this a good choice as I just use my computer to do office work
Maybe. There are many of those CPUs. There's also a possibility that an Intel based PC might be better. For those that know a little about PCs we don't apply blanket statements and as such vague questions such as these don't have an answer. On top of that the CPU/APU is but a few pixels of the entire pic. RAM amounts, GPU and other components play an equal part in determining the "fit" of a PC.