Recently, I did a lot of beta reading for bookish friends, and I am extremely grateful for this experience. At a certain extent, this is not exactly my first experience of this kind, as I was doing this type of reading for a long time already. The difference was that I was calling it differently: something like 'helping my friends to improve their writing'. And this is in fact the essence of beta reading.
The person who is doing it is usually part of the 'inner circle' of the writer, online or in real life, sharing common interests and with enough free time and expertise to make suggestions for improving the story and characters. You should not have to be a graduate of philology, but to have the lust for reading.
For those used with the usual academic chores, it can be a similar task with the proof reading or cross reading, except that in this case, the beta reading process is taking place at various stage of the writing process. It can start with the first draft of the manuscript and can continue later on during the various elaboration stages of the manuscript.
Even though many can consider working as full time beta readers, with a proper paid remuneration for their efforts, I believe that doing it for free is part of my gratitude of being included as a reliable reading source and a person able to give suggestions. Also, as a reader-in-process myself, I am enormously learning from such experiences, ideas and thoughts helpful for my further writing.
There are some sensitive aspects that are also important when dealing with the beta reading process. As generally in life, it is very important to be careful how to express your opinions and suggestions. I grew up with a high respect for everything that has connection with the written word and I also know how difficult is the writing process. During the sometimes difficult choice of words, the writer frequently put into motion a lot of energy and inner sensibilities. When the beta reader is rude and try to diminish the work he or she was given for consideration, without a specific explanation of the reasons, the writer can feel it more as a personal drama: it is the feeling of the failure of months, maybe years, of hard work, maybe without a proper financial support and stealing time from family. I suppose that except for the geniuses, none of the big writers were happy themselves with their first draft. By taking the risk to submit this original variant to comments and suggestions, he or she shows interest for reaching a better writing stage. Thus, it is very important that the beta reader has a certain human sensitivity as well, and is able to use his reading and eventually writing experience for helping the writer to improve, instead of simply destroying by aggressive words the entire work.
As for me, the experience of the last weeks of being a beta reader were extremely rewarding and when the time allows, I will try to repeat the experience as often as possible.