You're probably not going to look at the 2013 BMW 1-Series for flat-out practicality--although if you're weighing it against a traditional sports car, it may impress as a better daily driver.
Whichever variant of the 1-Series you're seeking, it's quite comfortable and easy to use--provided you're not thinking about using the back seat too much. Laid out like 2+2s more than proper four-seaters, the 1-Series Coupe and Convertible models offer plenty of comfort up front for full-grown adults, with the rear seat best left to kids.
The trunk itself is reasonably roomy, even in convertibled, while a pass-through split-folding rear seat offers more cargo space for longer or larger items.
Considering that the BMW 1-Series is the low-priced entry point into BMW's lineup, its interior materials are quite impressive and build quality is strong. They're not quite up to the standards of the latest 3-Series and 5-Series models in most respects. The one thing that's noticeable is that trims and plastics are slightly lower-grade. Cabin noise is commendably low, with wind and road rumble well-controlled, even in the convertible--so that stands as a big benefit over a number of other performance cars.
In general, on-the-road comfort is good, but it does depend on some of the performance options chosen. The low-profile tires with larger 17- or 18-inch wheels--as used in the 135is as well, or with the M Sport package--can create more ride harshness.