The 55-300 takes nice, sharp photos, and focuses fast enough if lighting is good. It's easier to lug around if taking a lot of pictures. I own the 55-300 and know its limitations, and it is a fine lens for the price.
From what I've read about the 70-300:
The 70-300 is a step up in build quality, focuses faster but you'll feel the weight if you are lugging it around for awhile.
So it depends on what you are going to use the lens for.
If you really want the best in quality, go for a fast 2.8 lens - great quality pictures with shallow depth of field and fast focusing.
NOTE: Lenses are a long-term purchase more than cameras are. I have a Sigma HSM 70-200 2.8 lens I bought long ago that still works great with my d90.
I am a novice, at best. It appears to me that the 70-300 has these unique characteristics: -Yes, the 70-300 has faster auto-focus. -The 70-300 is an FX lens that is both fully FX and DX functional. The 55-300 is a DX lens, therefore it will cause sizing limitations if used on a FX digital camera. -The 70-300 is heavier and larger.
1. 55-300 has both auto and mannual setting on it, but 70-300 has M/A and M. M/A means instant manual overwrite, M/A is pretty important feature. 70-300 is better for sports shoot. 2. 70-300 has a "G" in it, which is not good : http://www.kenrockwell.com/nikon/nikortek.htm#g, but that is new "Norm" that Nikon decide to do. 3. 55-300(309$) is 200$ cheaper than 70-300(509$) based on amazon on 07/30/2011. 4. 55-300(1.2lb) is 0.4 lb lighter than 70-300(1.6lbs) due to its plastic part(mount etc) 5. 55-300 is slower in focus than 70-300, and perform worse than 70-300 in 300 range, so 70-300 is better for sports shoot. 6. 55-300 is DX only, while 70-300 can be used in both FX and DX camera.
I have a D7000. I bought the 55-300mm vrii as a backup/travel when I cannot take my longer/faster lenses. It is also convenient for professional sports events that only allow small lenses. This is a low end lens, so I did not expect much, but it meets its purpose. I am actually surprised how inexpensive it is considering it has vr ii. I had the 18-200 mm for a while (which I loved) but I really needed longer reach of the 300mm for sports, etc. Although I read somewhat better reviews about the 70-300 mm, I figured if I am only carrying one lens, I might as well go wider so that I can pics of friends without having to step too far away. Originally, I bought the expensive 28-300mm and returned the same day. It is 3x more expensive! I did not want to spend more than $300 for a backup/travel lens. If you are serious about photography and can afford it, I recommend that you buy the 24-70mm f/2.8 and then the 70-200mm f/8 vrii. If you need more reach get the 1.7x vrii teleconverter. For wider angle, I would get the 10-24 mm for DX users.
While the 70-300 is better able to stand up to abuse, and not limited on a polarizing filter, a recent Pop Photo response to a letter implies the 55-300 may be a bit sharper (July or Aug. issue) and says the 55-300 is "a steal."
The 55-300 has a metal mount, not plastic. The 200 has a plastic mount.
What i HATE is the lens hood that comes with this lens. Extremely fragile.
The 55-300 obviously has more bang for the buck. Go with the 55-300 for the savings if you don't plan to be on the 300mm end very much. It's best about 270mm. The 70-300mm is better than the 55-300mm on the 300mm end.
In regards to Yug's comment about the 1.5x zoom factor ....
This is not entirely correct as any lens will give you a 1.5x zoom on a DX camera, even a lens designed only for a DX camera. So either lens will give you the same field of view when zoomed to the same focal length.
That 1.5x crop factor applies to the 55-300 also. In fact, it applies to any lens on a DX format camera. It's not actually zoom, rather it is a crop from the center of the image circle cast by a lens designed for a full 35mm (24mm x 36mm) slide. The focal length, however, is the same on FX and DX so the relative magnification of objects at various distances from the focal plane will be the same on FX and DX, but the field of view will be smaller on DX than it is on FX.
The less expensive zoom lens is usually the front element of the lens is rotated during focus or zoom. If you're used this lens with the cir filter, it will be a problem! In this case, the 55-300mm front element of the lens is moving during focus or zooming.
The Nikon 55-300mm VR is a plastic lens with a metal mount, which is easy to carry and handle due to its low weight. Although the lens has a total of 17 optical elements in 11 groups, it weighs only 580 grams.