Just to make it easier to answer your concerns, it would be nice to get more information what it is you do not like.
On a general note : It is very, very common to feel a bit lost with a new camera or new lens. Every camera or lens are slightly different, and it takes time and a lot of shooting to adopt. Changing a camera means you get a new viewfinder, a new AF system, different timing in shutter activation, buttons and wheels on lightly different places, different (and usually more) menu options and so on. And that is just the handling, also the image files will look different.
I'm happy user with the D70 using a 18-55 VR lenses, two days ago, i bougth a D90, whenever I found the old D70 more practical,
What do you mean by "practical"? Easier to work with?
better photo quality compared with the D90.
Try to describe more in detail what it you do not like, preferably with examples if possible.
Technically, the D90 sensor outperforms the D70 sensor in almost every way. But it is quite different, meaning there is a bit of adjustment to do. Some differences:
- Keep in mind the D70 has a unusually weak anti-alias filter, meaning images will look very sharp and crisp out of the camera. Part of this is real details and sharpness, parts of it is not ... Anyway, you will need to add more sharpening to your D90 images - and this is not just an issue of the D90, it is the D70 which is a bit unusual.
- Also keep in mind the D90 has a bit different tone curve, meaning images often will look a bit brighter, a bit more washed out. Again something which can be adjusted to have the D90 behave more like the D70, but in honesty, the D90 gives more 'truthful' images, where the D70 adds a bit of punch that really wasn't there

- The D90 gives slightly different, and in most cases, better colors. It has different color filters in the sensor, meaning things will look different. And it also have slightly different processing of image data after it leaves the sensor.
The new D-lightging feature is very confused to me, I can view good pictures in the LCD camera display, but when I transfer it to laptop, the quality is not good.
Question:
Users from D70 is recommended upgrade to D90 ?
I don't know the D200, but think this is more suitable for D70 users upgrading .
I still have my beaten up old D70s, hardly ever use it any more, mostly kept for nostalgic reasons ... But, I did shoot for two years with the D200, have shot a few thousand images wit D90 (and D5000), and a bunch of other cameras (I work part time as a photographer, part time technical journalist, and also teach introduction classes in photography and I do test out many new camera models).
The D90 in terms of image quality easily trumps the D70 with a wide margin, particularly in terms of dynamic range and low light performance. It also beats both the D80 and D200 (which both are better then D70, but less noticeably).
The D200 is a bit of a different camera also, it is sturdier built, has more external controls, better viewfinder, is faster overall, has better AF and ... Well, better everything. It is the older sibling of D300 which is in the same class, but which basically has the same sensor as D90 (noticeably better then D200).
My advice: Accept the D90 is not a new D70, it is a different camera, and for almost every photographic purpose, a better one. But it takes some time to get used to it, and the different images it produces.
Even among pro shooters, many are reluctant to switch camera unless they know they have some time to get used to the newer one. You definately do not want to switch in the middle of an assignment, because things will, intevitably, be different.
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I don't suffer from insanity, I enjoy every moment of it!
By the way, film is not dead.
It just smell funny