Ok, so next up to unity3D

Unity3D is again used as common term for several things:
-A web plugin technology allowing to playback unity content in various browsers
- a game engine and editor that allows to create unity3D content

So how does it work? One downloads the unity IDE, available in cheaper indy and more expensive pro forms,also as trial.
Once installed as flash developer one can expect quite a surpirse when opening the IDE (development tool) for the first time:
It opens up with a demo project and one can see a pretty lush 3D island scene in the scene view.
One can test the game right away which feels sorta like walking through a FarCry environment. Not exactly that level,but years further than other web technologies and regarding unity´s features one could basically do things on current gen console game level.
There are several views in the tool, one for editing the content visually in the scene, one which is close to the flash library,so asset handling and overview, then there´s the game preview view where one can test the game at any point in development.
There are also various other views,like also one for editing timeline animations or a baisc code editor.
Overall though, yes,ts obvious at first glance this is a tool for highend game creation and heavily focussed in every bit on that usage.

Coding:
One can code in javascript aswell as in C# and also mix and combine both inside a project pretty seamlessly.
At the end it doesn´t matter much which of the two languages are used because both are compiled down to machine closer level during build process.
Javascript runs at better performance when one uses strict datatyping there,too, but overall no matter if one does that or not code execution performance and overall performance is way better than in flash.
One can add functions in the script which are executed on Update or LateUpdate, sounds like onClipEvent EnterFrame to anyone?
Coding feels very much like in a flash IDE AS1 project,for the good and the bad: One essentially writes script files and then drags them onto objects.
So i´d more call it a symbiosis of AS1 coding manners (putting code directly onto/into display objects) and AS3 (usually writing seperate AS class files).
As i said the syntax can be in Javascript,so close to AS1 or C#,so closer to AS3 depending on personal preference.
What i like is that one can declare variables as publicly viewable in the IDE or not,in case one has it public one can select an asset with a scruipt attached to it and set the value of variables in input textfields etc, like setting parameters of components in the flash ide. One can also create project independently reusable versions of assets quite easily so its overall,yes,very similar to components besides one can edit them in nicer fashion.

Graphics:
On the graphical side unity has pretty nice downscaling of visual fidelity, one can use features of highend graphic cards but also have content scaled down to run on way older systems.
Inside the editor graphical 3D content editing goes very seamles,one can nicely position and slightly modify visual assets.
Regarding 3D models i liked it that it can handle way more formats than XNA and also that it has nice workflow functionality such as beeing able to set which frames of animation belong together,give them a labelname and then make the model jump to a certain labelled animation.
Yes,sorta like gotoandplay,just with 3d models.
This is a very simplified explanation though, there´s lots more to its model handling abilities, among those keypoints being one can ease from one animation to another,combine several ones together and give weights of importance to animations.
To give a simple example we have a running animation for our model,a shooting animation,too and we can ease from one to the other,alos lay one on top of the other so the dude shoots while running etc.
Also it has nice features for manipulating models,like moving parts,also on bone level if one wants.
This is all done in a way that is a huge timesaver compared to doing all codeside with no visual clues in say handling 3d models in flash or xna.
(One can do all codeside,too though,of course)
I could go on listing various very nice features,like editing 3d heightmap terrains nicely or tons of other things, i most like the out of the box ageia physics support though.
Realistic physics sims for any object out of the box on highest industry standard level. Yummy.

Deploy of games:
As i said there´s the web plugin, it has way lower penetration numbers than Flash or even Shockwave right now of course but i´m sure that´ll change soon and regarding what kind of impressive things one can do in unity compared to the other technologies and then if one uses those other technologies instead what kind of hardware requirements those other technologies then suddenly have due to the lousy performance they achieve on a certain level system i wouldn´t mind this point a lot if its about wanting to create highend grade 3D content for the web. Also penetration numbers are raising quickly and bigger portals already run one or some unity games or are getting into supporting them now.
Next up there´s standalone deployment, as web deployment for Mac and PC.
Then it was announced that now one can also deploy to the Wii (for that one also has to become a Licensed Wii developer though) and then they´re also working on Iphone support which should be available soon.

Now there are also some restrictiosns and limitations as with pretty much everything in life:
With unity to me the biggest one was getting a mac,since the IDE is not available for PC right now. One could run Mac OS on a PC but then has to expect various issues on all ends since yeah,its just not the real deal.
Next up the pro version is for a seasoned commercially working developer affordable but to a small indy not exactly cheap,the Indy version lacks several key features the pro version has.
Next up if you´re just into doing 2D games or other sorts of games for which flash would be perfectly suitable,then yeah,there´s the question why you choose a less widespread plugin techology if its about web deployment.
There are also several minor and 2-3 a bit bigger issues i have with the ide,but since its all in all so much more advanced than comparable things i won´t list em lengthy now.

So overall if you´re into doing medium-highend 3D content (and i mean console/pc retail game grade highend ) then unity is well worth a look.

To sum up: No,none of these will be an instant flash killer or make flash completely worthless or anything similar.
Each has different pros and cons and is suitable for doing different things on partially different platforms.
Hope you got a small insight on these and found it interesting and i didn´t waste ages writing this for no reason