ok, so you are saying to buy Tamron SP AF 70-300mm F/4-5,6 Di VC USD (for Canon Digital SLR) Lens
In reviews I am seeing a very good review almost everywhere.. also price difference between it and corresponding canon lens is almost 10K..so thinking of buying it.
Want to buy it for bird photography and also use general purpose.
Will post photos of Tamron 17-55 2.8 later
for bird photography even 300mm will not be enough but it will be good start..try the lens before buying as i have found myself using 55-250/70-300 less frequently( though it will be great for street photography)