I love the value resorts, but I confess that I haven't stayed there for over a year and a half now. Before that we stayed at all of them multiple times. Pop is my favourite, but AS Movies is my Mom's favourite. Of the AS, I like preferred in Music the best. DH likes ASSp best. Honestly, I think that they are all pretty comparable.
The rooms are small and there are two double beds. Amenities are pretty basic, with simple, but nicely themed, pools and a food court for dining. The bus stops have roped lines, but no cover from the elements. Buses are frequent, however, in our experience.
I would stay at a value again if budget required, but I have to confess that as I have gotten older, the moderates/deluxes are more my cup of tea. DH and I feel a bit cramped in a value room, even though everything that you really need is here. We don't just sleep and shower in the rooms anymore, so that makes a difference. We spend a lot of time relaxing at the resort. As a result, for us, a moderate or deluxe works better.
I wouldn't worry unduly about negative reviews - it is likely that some of these are due to people having higher expectations of the resorts and being disappointed in what they get for the money paid. Value resorts are a good value for WDW, but they wouldn't get those prices in very many locations in the 'real world', IMO. PLUS, You will see negative reviews of all the Disney resorts at some point. Some poor experiences are likely anywhere.
If you like the look of ASMu, I would simply do my research in order to have realistic expectations and then book there and enjoy the stay! If you do encounter a problem, CM's will work with you to fix the situation.
Enjoy!