Ruman Tandoori is on the busy Blackstock Road that runs along the border of Islington and Hackney. It is busy for people and traffic, but also numerous good restaurants offering good value food. If you search Tripadvisor, you may find some great ones (try Au Lac) and Ruman Tandoori certainly qualifies too.
The restaurant is certainly nothing to look at and although has recently had a coat of paint it looks like it could do with another. It is traditional Indian restaurant shabby chic, but fresh and clean. The welcome is warm and the food fantastic. It isn't gourmet curry, it is "let's go for a pint and a Madras" curry and it does it exceptionally well; moist chicken, tender lamb, clean sauces.
Their website includes a comprehensive menu and allows take away ordering and table reservation.
It has got quite a reputation locally. Its take away service is very busy, so some nights it may not be busy inside, don't let that and the shabby chic put you off, the food is delicious.