I had an '02 version of what you're looking at. 3rd gear synchro was always stubborn from day 1, and finally went out at around 19K.
The car went through 2 sets of front struts by 15,000 miles until they found a TSB about front suspension mount bolts. This I'm sure they've addressed by now. But in case they haven't, listen closely for a THUNK in the front suspension when driving over small road irregularities at parking lot speeds. Speed bumps won't do it.
The initial problem with the car, again since new, was a glitch in the ECM that would cut power and keep it cut while driving. One minute it would be fine, the next minute it would decide it wanted to put out about 100hp instead of 245. Flooring the throttle just yeilded a lot of intake noise but no real acceleration. Shutting off and re-starting cleared it up...sometimes for the rest of the day, sometimes for 15 minutes. Another out-of-the-blue TSB got me a free ECU reflash for that issue.
Due to all the time I'd spend rotting at the dealership, I became so disappointed with this car that I traded it in on a 2004 Mazda 3 while it was on the lift and the transmission was laying on the workbench. It didn't help that the dealer took 2 attempts to repair the 3rd gear synchro, totalling 22 days in the shop. Thankfully, I had opted for the upgraded warranty, which paid for the rental car for the duration.
It's probably going to be a while longer before the Nissan bad taste gets out of my mouth. But I sure like the looks of the most recent Altima. Very nice looking car. Hope you have better luck than I.