Well, not quite the best. I'd like to contradict the previous reviewer.
Iyer's definitely is a nice place to be, there are some downsides to this venue though: First of all it's pretty cramped there; even if you're the only person inside, you might feel cramped due to the cheek by jowl tables and chairs. Once there are few more people, the place becomes crowded very easily. I claim, usually you don't want to stay there for very long, unless it's raining outside.
Apart from this Iyer's is more or less alright. The food seems to me slightly overpriced, since the portions aren't generous at all, but it looks keen and tastes good. After all the venue is clean and bright and the staff is friendly and helpful.
Go there if you want to experience decent Indian food, but don't go there if you are really hungry or if you want to stay for longer.
There are not many alternatives in Cork, that's true, but you still can do better.
Cons: slightly overpriced, cramped, not for big appetite