The Novara Big Buzz is a decent bike and one that you will enjoy riding. Although I would personally prefer to buy bikes at that level from a dedicated bike store, it's a fine choice if you test ride it and like it. It's a fair price, the componentry is good and REI will back the product.
This is my opinion based on owning 18 bicycles of different types at this time, being a bicycle mechanic, a former bike shop employee and having owned, ridden, raced, toured and otherwise rolled around on many bicycles.
If you're still reading this thread by now, there are a few things posted above which may have concerned you that I'll try to address real quickly:
--You can get a better deal on Craigslist. Totally true, if you know what you're doing and what you're after. Bikes sell for about half-retail when used, generally. However, it's Caveat Emptor, there are no returns and no warranty. If you want the advantage of retail, you pay for it.
--You can get the same bike at Target (or Walmart or Dicks Sporting Goods). Totally false and wrong. The big-box stores do sell bikes at enticing prices but they are not the same thing, despite occasionally bearing recognizeable brand names. If you go to a Toy Store to buy a car, you get a toy car. Those are toy bikes using vastly lower-grade components and materials and they are assembled by the same fella that puts together the modular desks and the display of laundry soap. Don't be fooled by fools on this one.
--You need "high end components" like XTR. This is baloney, but you should entertain yourself by googling "XTR rear derailleur". See how much that costs, ha ha!! The X5 components on the Novara are more than fine for city riding, are easily tuned and will last years. If the time comes that you're ready to mountain bike on real trails, road ride for 30 miles a shot or etc... the bike you'll upgrade to should have better, lighter, smoother stuff and you'll happily pay more for it. In the meantime, the SRAM X5 will be great.
--Disc Brakes. Yes, you want these. Although the particular brakes on the bike aren't my favorites, they're fine and will work nicely. Importantly, disc brakes are much easier to manipulate when you put the wheels on and off the bike, aren't affected by rain and don't care if your wheel has a slight wobble. Although they "came from" the need for off-road racing brake power, they're now on all kinds of bikes because they simply work and are "easy". Go with the discs and never worry about it.
--You can get the same bike from China. Well, the Novaras, and about 80% of all other bikes, are made in China. However, you can't order up a Novara-branded bike from Alibaba. You can get similar bikes, perhaps at less money and weight, from chain stores such as Performance Bikes. If you have one local, I suggest you go shop there and pay attention to sales and their membership program like REI's (except you can cash it out immediately upon buying a bike to use the credit for your new helmet, etc..)
Good luck on your quest to get out there on two wheels!