I actually have done this exact kit, turned out fairly good. Basically a Guiness clone, but it was only my second batch so I stuck to the recipe, now of course because I always wonder what could have changed or I could have done better. After brewing 5 batches 2 of which I have greatly changed variations from the recipe and so far so good I have thought of a few things I may have done differently with this stout.
1. Its Irish, make it Irish - get 4 oz dark oak chips/cubes and soak in 6-8 oz jameson whiskey for 5-7 days You can then drain off the whiskey, rack the beer on top of the oak and let ferment in secondary for 2-3 weeks. At time of bottling you can add back in the jameson whiskey you removed to taste or into only specific bottles..you can also leave the jameson in secondary let it go for 3-4 weeks and bottle.
2. at time of bottling you can mess with various extracts - vanilla, chocolate, or others to add to a few of the bottles to see variations.
3. I would also probably throw in 8-12 oz DME (golden to not change much else of beer) and if your feeling crazy you could have some fun adding some Turbinado sugar toward end of the boil
There are a million variations to that kit, but its a very good place to start for a basic dry stout, the only downside if the OG On the bright side using #1 and/or #3 above you can help that out a little and get it up in the high 5's or about 6%
Let me know if you end up doing any of these options as I will be curious how they turn out.