My brother's lived on Mountshannon Rd. for the past 10 years, and he wouldn't hesitate to recommend it. They have very good neighbours, and there are plenty of family homes on the road. Location couldn't be better, especially since the Luas came. Yes, there are some dodgy areas within 500m, but they've never had a hint of trouble. Personally, I'm not sure Kilmainham village will ever develop in the same way as (for example) Ranelagh has due to the South Circular being so busy, but the Hilton and surrounding developments have and will have a very positive effect.
The road itself though is a bit of a peaceful enclave: I know it would take a lot to get him to move.
To the OP: PM me if you want more specific details on anything: I know the area quite well.