I really hope they don't start pushing Mega Evolutions onto too many Pokémon. There are far too many that actually deserve regular evolutions more than anything, and I think Audino was one of them. I think the lack of a hold item (Apart from its Mega Stone, obviously) is going to be far too big of a handicap for it to function well, especially seeing as it won't even have Regenerator any more, and Audino lacks any really usable recovery moves. Not to mention that pretty much every other defensive Mega Pokémon has atleast decent offensive stats, whereas Mega Audino will probably have next to none. I can't really imagine many people would use it over other Mega Pokémon, even if it probably would have great mixed bulk.
I do really like the design, however.
Mega Slowbro is almost in the same boat, except it'll probably be saved by an actual offensive prescence and the fact it gets Slack Off. Can't think of much else to say about it really. The design is ok, but nothing too special, and its ability is too situational to be of any real use. The stats will definitely be what determines if it gets used or not.
Overall, really confused about the decision to create these Mega Pokémon.