Summary I am a photographic enthusiast. Although I can confidently say I know more about photography than most, I'm not a seasoned or contracted professional. Stepping up from a line of prosumer cameras, the Sony took the next step very well. Or should I say Konica-Minolta, since the Sony A100 ... Expand full review
Summary: I am a photographic enthusiast. Although I can confidently say I know more about photography than most, I'm not a seasoned or contracted professional. Stepping up from a line of prosumer cameras, the Sony took the next step very well. Or should I say Konica-Minolta, since the Sony A100 is based off a slightly improved design of the KM5D?
Handling/Build:
For one thing, the build is a strong plastic and handles much more confidently than the Rebel XT, which is highly regarded as the benchmark for low-end dSLR cameras. That extra groove in the handgrip feels great. The shutter button is a little further back than preferred, as I tended to put my finger on the jog dial, but it took less than a day to get used to it. It’s not too heavy and inspires confidence in the build.
Image Quality/Speeds:
Anything up to ISO400 is shot without worry. Most all ISO800 pictures come out just fine, but expect to post-edit about 15% of them for noise. This may also be due to not-so-optimal shooting settings (user fault). Anyway, they're all usable and definitely recoverable. The noise at ISO1600 isn't unusable, but just be wary that you will be postediting around 50-60% of the pictures for noise before using them. In this arena, Canon's CMOS will win. But how often do you shoot in dark attics?
The autofocus is precise, but I still long for the more covert orange/red light metering for metering dark areas, found on other cameras. One great thing that is seldom mentioned about the Sony is its processing speeds (writing AND accessing). It is ridiculously-blazingly-super fast. A 10mp RAW file comes up instantly and zooming in on your picture for details comes without hesitation. You are seldom waiting for the Sony, but also look into getting a 120x or above card (SanDisk Extreme III). I’d use as low as an Ultra II at minimum.
Image quality on the whole is great. The colors are quite accurate and I think most people will be content leaving the camera on the "Vivid" color setting with a +1 sharpening. The kit lens, a highly regarded and now rebadged Konica Minolta lens, works VERY well with the camera in “stock” form. Unlike what Canon and Nikon give you in their kit lens, you might actually keep the Sony 18-70mm f/4.5-5.6 for longer than a year. Save those ebay fees for your previous camera. 
Lenses/Image Stabilization:
With Sony's Super Steadyshot stabilization sensor (alliteration galore), you can be confident to get about 2-stops out of it and up to what they claim a 3.5 stops. For reference, 1/60 shutter speed is the minimum recommended for handheld shots for most situations. You can take sharp photos with the Sony from 1/30 seconds with confidence against blurriness. At 1/15, you'll notice that 85% of shots will come out clear. I've taken up to a 1" handheld shot which came out clear (usually a take three consecutive shots, delete two rule works quite well). For this reason, you can venture into realms you wouldn't for the price you pay. Since IS (image stabilization) is built into the camera, ALL your lenses are IS. Check online for lenses and you'll notice most KM lenses are under $300, whereas prices vary greatly with Nikon/Canon averaging a little higher. With old lenses on the market and newer third party Tokina, Sigma, and Tamron lenses available, MOST of the KM world is a great deal.
For Professionals:
With the Minolta G lenses and upcoming Zeiss lenses, you may be inclined to buy the Sony thinking, “There are some awesome lenses out there for future upgrades,” but Sony's trend of overcharging isn't an exception to the Alpha series. For the price of a Zeiss or G lens, you can buy a Canon Image Stabilized (IS) L-series lens or a Nikon VR (vibration reduction) G-series lens AND STILL KEEP SOME HEFTY CHANGE. For professionals, I would leave it up to Nikon/Canon... for now. You'd be paying too much for lenses and praying that Sony fixes ISO1600 and offers 3200 in their next camera (hopefully shooting at 5fps).
The Bottomline:
I had to compare this camera with the Nikon D80, Canon Rebel XT (350D), and Canon 30D. The Rebel is a great toy for fast shooting in dark situations, but the small screen and lack of options hold it back. The D80 has better editing menus and probably will have better low-light shooting than the Sony, despite using the same/similar sensor. The Sony already has had similar ISO performance and shoots slightly better image quality than the highly reveled Nikon D200 during testing on other sites. But the Sony offers IS built-in, whereas with Canon and Nikon you'd have to pay a high premium to get it (though lens mounted IS systems are probably slightly better).
Let's say you want a comparable range of lenses for your purchase. You'll spend under $1600 for the Sony body and about three good lenses. You'll spend probably $2500 for the Canon/Nikon body with an IS-featured lens for long range and a sub par kit lens. Up to around $2400, you'll be generally better off with the Sony. But if you want an L-series short-range, IS long range lens, then Canon/Nikon is for you, because you'll be spending that same amount on just one G-lens or Zeiss from Sony. And that's when it isn't worth it (spending over $2400 total in the long run). If you own a KM5D or 7D, don’t bother thinking twice – this camera is good, but it isn’t worth the $900 “upgrade.” You already have nearly all the features and 6-megapixels is plenty enough for the following year.
When you add it all up, the A100 is for the masses, but not the elite. You'll be happier with a clear picture on your computer than most blur-shooting competing models, despite spending a wise $100-300 more. You can better check for quality on its fat screen. It’s a great, fun camera to use and you’ll get amazing results out of the box. But if you plan to go pro in the near future, Sony doesn't offer the speed you'll need to do it at a good price -- yet.
