First DSLR

I have owned several P&S digicams over the last 5 years but this is my first DSLR. After 1 month of casual use I am happy overall but that came only after understanding what the camera is good at and what you can change to make it better. I have a bag full of 20-year old Minolta equipment that hadn't seen any use for these same five years - digital is so much better that I put up with the P&S shortcomings.
I chose the Sony primarily because I had these lenses that, I knew from my film days, produced fantastic pictures and that would save me some money not having to replace them (especially since it seems buying equivalent lenses today would break the bank). The 18-70 kit lens does not come close to the detail my old lenses capture and it has a lot more chroma artifacts. In my opinion, the kit lens focuses slightly faster however and it focuses so close it is a cheap way to get some basic macro ability. If you are on a tight budget however just go ahead and get the camera/kit because it still takes awesome pictures and you can add lenses later on.
My old Minolta Maxxums were metal bodies and so it seems strange to hold a camera that is so light by comparison. At first I felt it was cheap construction but after using the camera I would say it 'feels and sounds' like it is well made. I think like most Sony gear, they are very good at creating quality 'consumer' goods. It does not 'feel' like the bigger Canons or Nikons but I would no longer label it as cheap. It is nice to hold and use.
The only direct comparisons I can make are to my daughter's Canon XSi and my friend's Nikon D40. It is easy to pick the Sony over that Nikon - the Sony is faster, nicer to use and has way better picture quality. The Canon is a much tougher contest. It takes excellent quality pics, has an awesome LCD screen and the Canon was much faster, out of the box, until I put a 300x CF card in the Sony. The Canon still has slightly better burst rates but now overall the Sony is just as fast with slightly less shutter lag which was the main reason for getting a DSLR in the first place. My Canon G9 was a great camera but way too slow.
I highly recommend any A350 owners get at least a 133x CF card if you want to do any amount of continuous snapping and since Sony made it UDMA compatible you might want to spring for at least the 266x cards that are UDMA. The difference in buffer upload time is huge. With a standard CF card, it can take up to 20-25 seconds for the buffer to clear a full load of RAW jpeg files. With the 300x card it takes 5-6 secs. flat and I can continue shooting. The faster card also allows the camera to keep shooting indefinitely at 2.5 to 3 fps under certain conditions: turn the d-RangeOptimizer off and set the focus method to Auto or Single. The d-R especially really slows the camera down after the initial 3-frame burst whether you are in RAW mode or not.
The Live View is awesome especially with the tilt screen but I find the optical viewfinder suffers a bit from being small and a little hard to get up close to because of the LCD screen sticking out from the body a bit. When I look through the XSi viewfinder it is big and bright (like my old Minolta's). But I tend to like to shoot odd angle shots from down low for example and that is very difficult to do without a tilting screen. Pivoting would be even better but maybe next time.
I recently purchased Sony's new HVL-58 flash and my satisfaction with my choice of cameras increased significantly. Nobody else has a flash like that and it completely changes the equation. The Canon or the Nikon cannot do bounce flash in portrait mode (the most likely time to want bounce flash) like this can plus the Sony has built in wireless flash. I am hooked on that setup. I just hold it above my head with my other hand or set it somewhere in the room to create a bit of creative lighting and shoot away. It is easy to use and the change in picture quality from on-camera flash shots is literally night and day. It is expensive however and Sony's other flashes are also wireless capable. They just can't do the portrait-bounce thing.
There is a lot of talk about high 'noise' levels at higher ISO compared to the top DSLR cameras and my own unofficial 'tests' of that seem to indicate it is true. So far I have not blown up any of my pictures enough to really see that as a negative. I prefer the quality of natural lighting or switching to add-on flash and still I have not found noise to be a problem. By using my older lenses which overall are faster than kit lenses tend to be, combined with IS I have been able to keep the ISO below 800 for everything anyway and below 800 there is no 'noise' to worry about.
I know Sony was going after the P&S shooter, who wanted to move into a DSLR, with the 300/350 cameras. Along the way I think they created a camera that has many 'serious' photographers re-thinking their DSLR preferences. Now, I feel good about being in Sony's camp. They are a very innovative and formidable company. Combined with the legacy from Minolta, also one of the most innovative photo equipment companies ever, I look forward to benefitting from all that again and again in the future.
Highly recommend it.