Too harsh a review and you come across as an embittered never was, a non-writer who's jealous of those who can. Too nice and you sound like a mewling sycophant!
Luckily, this book - without being perfect - is obviously not rubbish but rather is an effectively written and tightly plotted thriller somewhat in the Rebus mode.
It starts well, with a firm authorial hand on the tiller as the narrative kicks off in faintly comedic strain. The various characters are introduced in a steady early stream and each proves to be engaging and interesting, while the central conceit of the title (a presumably mentally ill man who speaks only in Beatles' lyrics, and the effect his passage through life has on those around him) is just odd enough to hold the attention.
All of which would be worthless if the plot was weak or uninvolving. Fortunately, the story of how Danny McColl collides with the terrible Finch family and appoints himself a sort of weirdly ineffectual protector for those who live in his new stair (including the Beatle Man) is well told by the author and comes to a satisfyingly twisted conclusion which ties up every loose end.
Don't get me wrong: like I said at he start, this book isn't perfect. There is perhaps a slight tendency to lean in the direction of caricature (Asian shopkeeper, Glaswegian wideboy, posh lawyer who likes a drink and the ladies and so on) and the writing does at times seem unsure if it wants to be a more chatty, less idiotic Irvine Welsh or a 'proper' gritty crime novel, but these failings - such as they are - are never enough to adversely effect the narrative.
All in all, this is both an excellent first novel and a good novel full-stop.