Went last year with RMI and had an excellent experience with knowledgeable and experienced guides. Ratio was 1 guide to 3 or 4 clients. I came solo and was lucky to be teamed up some great fellow climbers, both on a skill and personal level (which is good since you are roped together after Camp Muir where RMI has their own hut). For my early July climb there were a total of around 20 clients - 5 of which didn't summit due to lack of conditioning or undisclosed medical conditions.
Certainly one of the tougher climbs I've done but very doable if you're in good shape. Winter hiking in the Whites and ADKs as prep helped, especially packing big and heavy, going with mountaineering boots, climbing in darkness with just a headlamp... I found the day of training on the mountain good and useful (self-arrest techniques, being roped up, crampon use, etc); food and liquids were more than sufficient throughout (in fact I used some the food for a climb of Mt Hood the day after returning..)
With any guided service YMMV, in my case I was lucky that it all came together perfectly (great guides and fellow climbers, perfect summit day conditions, personally in good shape and injury free, clear about my expectations which was to have a 'real mountaineering' experience where summitting would always be optional). I could easily see that if any one of these components was 'off' the experience could become less than positive. Some of that can be controlled pre-climb with proper training both physically and mentally, some less so when on the mountain like not handling the altitude well or being roped up with a guide or fellow climber who aren't on same page as you.
I believe May climbs tend to be a little trickier weather wise with a greater frequency of teams not summitting - but then again a climb 2-3 days prior to my climb failed to summit due to bad weather...
Good luck!