I recently purchased a Tamron AF 90mm f/2.8 Di SP Macro Lens and was intending to employ the above title in an ironic sense, such that my only real complaint was that I hadn't purchased the lens any sooner. When using the lens on a number of objects around the back yard, I was really pleased and enjoying the lens, despite what I believe its one real limitation - the extending front element as one focuses closes to 1:1 (as opposed to internal focusing mechanisms) - which I was willing to overlook because I knew of it going into the purchase. But then, when I took the lens with me out to a local hiking trail, I discovered that for some reason it would not focus to infinity; in fact, it wouldn't focus any further out than about ten feet.
So I exchanged it for a Tokina AF 100mm f/2.8 AT-X Pro Macro Lens, which as it turned out, would only intermittently choose to communicate with my camera body. Next stop: Canon EF 100mm f/2.8 Macro USM Lens. And I will certainly be posting results, as well as any complaints.