Is Nikon D90 a good camera for getting started in SLR photography?

It is certainly quite sufficient for starting out.

Until you actually need something better, there is no reason to buy a different camera body.

It's a perfectly good camera, even by current standards.. Sensors have gotten slightly better since the D90 as far as noise goes. For video, it's passe. As for pixel count, don't get excited by this. The D90 can produce nice large prints without problem.

SLR refer to film cameras while DSLR refers to digital cameras. Sounds like you haven't given the camera you own a fair trial. Doing that and comparing to what's available today will increase your knowledge base and make for a much better decision on your part. For instance, will the lenses made today fit your D90?

If the answer is yes then the D90 might make a good back-up camera and it would be wise to keep it.

The D90 is a very good camera. I had one and gave it to my son earlier this year when I went to a D7100. It is still a fine camera and we expect to get several more years use out of it.

Yes it's a great camera. Not just for starting on but should do you a good few years of use. It's above the current entry level spec of the Nikon range.

its a good camera and for the price (250-300 used great condition w box etc) you can't go wrong. its an excellent camera to start with. it was upgraded by the D7000/D7100 but still is more useful then the d5000/d3000 series even though they are a lot newer.

Yes. It's one of those modern 'classics' which exceed users' expectations.

Only if you need to do a lot of shooting indoors or in low light, or need modern video would you need to get a D7100.

To get a noticeable leap in terms of image quality you would need to get a camera with a 35mm sensor.