The Mercedes TT V8 throws down similar performance numbers and does not have ANY of those problems.
The battery issue is still an issue...recommended replacement every oil change (10,000 miles)

After that first replacement, the battery tab is on the owner.
As far as the oil burn, that isn't the only problem. If you really did read the BMW forum, you will see that the engine has problems ranging from stretched timing chains to bad fuel injectors. All this on an engine that is as new as 3 years old. BMW updated the N63 in '13 but there are still reports of that engine giving owners problems such as rough starts, battery issues, etc. To top it off, some guys have reported poor performance even after the CCP was performed.
The general consensus on the BMW forums is that BMW still has not zeroed in on the exact problem.
At least BMW has owned up to the problems and is taking care of customers that are out of warranty as well. It sure is suspect though that they didn't want to call it a recall and instead called it something much nicer sounding..."Customer Care Package."
I was actually looking at used 550i's and 550i Gran Turismo's before I decided to purchase my R-Spec at lease end. Prices have been hit hard because of all these problems. There's a certified 550i GT sitting on a dealer lot here in Texas that has been on the market since February. They first listed the vehicle at $53,500 and now they're asking $40,500.
If you don't mind getting to know your service adviser really well, owning this V8 really won't be a problem. I would stay far, far away from one of these vehicles out of warranty however. My '08 550i hasn't been the most reliable vehicle ever, but it isn't unreasonable even out of warranty and with 135,000 miles on it.