Summary: I decided to go with the EOS 50D after reading tons of reviews, and being told for years I was wasting my time with Pentax. I went from a Pentax k20 to this, I can say the image quality was a step up, but that's about it. I could not stand the feel of the body in my hand, the controls felt somehow clunky, I did not like the interface, or battery life. I ended up selling the canon and picked up a Pentax k-5II, in my opinion a much better camera.
Summary: I bought the 50d as a backup camera to my 5d MkII. It is an outstanding camera that truly comes in extremely close to the 5d in performance and features, at a fraction of the cost. I've used it on a shoot as a second camera (in lieu of changing lenses on my primary) and found that I really couldn't tell which camera had taken the pictures without checking the metadata.
Summary: I bought this one used for sports and got good use out of it for all of two month. I'm a novice having only recently upgraded from an S100 to this DSLR but the controls were easy to navigate. I had a harder time migrating from the 50D to the 70D (and 7D) than when I first got the 50D. All was well until I made the mistake of putting a can of creme soda in my bag which ruptured.
Summary: This is a hefty SLR which handles very well to people with larger hands. The build quality is top notch and so it is heavy. My concern is with image quality: up to ISO 800 the image is great but above ISO 800, it is grainy (predominantly chroma noise) and lacks details.
Pros: Build quality, hand grip is substantial, image quality at lower iso
Cons: Images above ISO 800 is ugly IMO (don't like the chroma noise), heavy
Summary: I am sorta joking about the title, but really, this has so many features I thought were only available on a 5D mkII! Silent Shutter Ultra-high FPS (With Magic Lantern) Video Recording Very clean ISO performance. (Can go up to ISO 3200 before noise becomes REALLY apparent, I shoot at ISO 800 most of the time!) Live View Gigantic, beautiful screen (Of course, I upgraded from the 20D...) All in all, I HIGHLY recommend this camera.
Summary: As for an advanced amateur photografer, this camera offers great opportunities. Camera limits me in no way. It requires good lens to show great pictures. Body feels so strong and durable, lays perfect inmy hand. It's very fast in operating. Slight disadvantage is known noise level of the sensor. But if kept in mind, it won't bother you. There are much newer cameras on the market now. I tried 60d. Great camera, but feels less sturdy and pro than mine.