The studies would indicate that glutamine is ineffectual for the purposes we require but anecdotal evidence would seem to oppose this. Too many guys use it and get good results. Myself included. The choice is yours but I try to use it as much as possible.
Benefits are said to include:
Raised GH output, enhanced immune system function, lowering of cortisol, increase in protein synthesis, decrease in protein breakdown, speeding up of glycogen storage and cell volumization.
If it only does some of the above to a limited extent then that is enough for me. I mainly notice an increase in condtion with no drop in bodyweight (GH increase possibly?), i.e. an increase in LBM.
Dose needs to be high to get the most out of it though - 20g plus per day in my view. Also it needs to be taken on an empty stomach if in the L-form (as opposed to peptides which are better if you can get them). Best taken first thing in the morning before anything else, before and after a workout and last thing at night.