Some oil usage is entirely normal and not necessarily indicative of a problem. Most all manufactuers state that consuming 1 QT of oil every 1,200 miles is acceptable, though I feel that is excessive and between all the cars my wife and I have owned, none consumed major amounts of oil. Our old 98 LGT wagon (EJ25) consumed about 1/2 QT every 3K miles and my wife's 07 Outback consumes about 300ml every 3K miles. My 03 Infiniti G35 consumed about 1/2 QT every 4K miles and my 96 Maxima consumed 1/2 QT every 5K miles. My 2012 WRX only has 5500 miles of which I've already done oil changes at 1,000 and 3,750 miles. I haven't observed any oil consumption, but initial oil changes have been so frequent that it's hard to monitor much. Many will tell you minor amounts of oil conumption is the sign of a strong motor. Also, oil consumption naturally will go up as oil breaks downs and looses viscosity. Lots of stop and go driving without full warm ups will kills oil much quicker than highway driving. Lots of unbruned off fuel in the oil kills it as the months pile on. Don't solely go by miles, also consider time, especially if you do lots of short distance city driving. My wife's Outback consumes no oil in the summer when the kids are out of school. Once they're in school and she's doing two daily 5 mile roundtrips to school, consumption starts up again.
FYI, LOTS of different makes of motors consume oils. Lots of Hondas, BMWs, Nissan products, Toyotas, etc drink oil. This isn't a Subaru specfic problem nor really is a "problem" in most cases.