The engine will last forever with ANY synthetic oil, quality filters, and reasonable OCI's like 7.5k or twice a year. This engine is easy on oil. But, the oil sump is small. Don't neglect the oil dipstick until the engine is broken in and consumption is nil.
Its a great commuter car for the money. Sentras tend to be a little rough around the edges.
Dealer discounts, rebates, and the redesign should make the leftovers a steal. I saw a local dealer advertising them for under $9k.
I've heard of the head gasket issues but some of the owners that I've talked to also were also negligent with maintenance. And, I haven't seen any statistics that the 1.8 was any worse than other vehicles. Basically, I seen head gaskets fail on just about every make and model.
To alleviate any head gasket anxiety, change the coolant & thermostat(use OEM) every 2 years, and use an antifreeze sealant like Barsleak, GM, BG44k, Alumaseal, Prestone, RadiatorSeal... Toss the sealer in when you take delivery of the car.
Or, prior to expiration of the powertrain warranty, get a UOA on the oil.
Nissan oil filter placement really is pathetic on some of the cars. Remote mount is the way to go if you are a backyard mechanic. But, I've never had any problem removing any Nissan oil filter. So it takes an extra minute and I'm more competent than the typical grease monkey.
If you practice jippylube service, it is wise to verify filter replacement. I know of several Nissans that had 3-4 quick-lube oil/filter changes. When I serviced them, they still had the gorilla installed tough to remove OEM factory filter from the factory, and not the quickeelube filter.
The transmission also shifts well. A move to a synthetic fluid will make winter shifting easier.