It's hard to define the best thing about Grandma's House. I can understand how not everyone has love for it, but I guess 'haters gonna hate'. The scriptwriting is quick, yet not needing for silly puns or naff sitcom-style laughter tracks. Much like Curb Your Enthusiasm, The Office or The Thick of It, it works of awkward wit and communication between stereotype characters. The character's would be nothing without some great performances (namely co-writer Amstell's, and the late Geoffrey Hutchings who gives a level-headed approach. In many ways he is the 'chorus' of the piece.) and the characters are created so well you could believe every second of it is written on Amstell's real life experiences.
To sum up, an excellent comedy-drama (where the drama is made easier to approach due to the comedy around it) and Amstell and Swimer should recieve many accolades for some of the best writing in recent years.