I always liked Runaway Brain. I saw it when it was first released theatrically in the UK with A Goofy Movie and then many times over when it was released on the VHS 'Mickey's Greatest Hits'. For the most part, I actually liked how Mickey was portrayed in MouseWorks. Not all the cartoons were great, but Mickey didn't seem too bland to me – the episodes with Mortimer particularly bring out a side of Mickey that's fun to watch. However, the big thing that Runaway Brain holds over all the Mickey cartoons released since are the fantastic production values and what must have been a massive budget – it just looks great with tons of little details and gags which make it worth a re-watch and lots of pauses. When Runaway Brain was released, I hoped they'd be more theatrical Mickey cartoons, but we've had to wait 18 years for 'Get a Horse', which will be the first Mickey cartoon to get such a deluxe treatment.
I think Runaway Brain is exciting and fun. I don't need every Mickey cartoon to be so loud and fast paced, but this one stands out as its own special big-budget thing, something that's a lot of fun and a little unexpected.
One thing this cartoon can't boast though is the catchy music I associate with Mickey Mouse cartoons. The score does its thing for sure, but the only catchy memorable melodies are quotes from other songs and heard in little snippets (e.g 'Steamboat Bill' used to reference 'Steamboat Willie'). The lower budget TV cartoons have had some perfect Mickey music – there's been some really great stuff to whistle in both MouseWorks and the new 2013 series.