Bought this lens to replace a Tamron 28-75 f2.8 that had served me well for 6 years. This lens is an excellent upgrade in all areas. The build quality is much better (but significantly larger and heavier), optics are outstanding, and the AF is faster and quieter.

Update 01/15/15: This lens has major auto focusing issues. I Have been testing this lens and adjusting my cameras focus adjustment for the last two weeks to no avail. This could be a defective copy. At the tele end, the focus is accurate about 75% of the time... not great.

Great lens, but I received a Japanese version. The investment is too large to run the risk of not being cover under the USA warranty.