Other reviewers class this programme as predictable and clichéd, and it might indeed be a little predictable at times, but the quality of the acting during the delivery of aforementioned predictable gags will make you laugh regardless.
The two leads Tom Stourton and particularly Charlotte Ritchie, as the siblings Dan and Hannah, really make the grade, and if you're a fan of crass-yet-clever British humour found elsewhere in shows such as 'The Inbetweeners' and 'Fresh Meat', you will probably find yourself binging the first 6 episodes of 'Siblings' in one sitting.
It truly is a great character comedy which ascends its formulaic appearance on paper with its delivery. Definitely worth a watch.