Problems with a D300? Hell no, man. I upgraded from the D80, and yeah, there have been moments where I've wondered if it was worth it...and then I opened the box and saw the D300 and was like, 'okay, that was worth it.' Seriously Kundalini, do it.
But, since I like ya, I'll get more in depth here for you.
I'll do it in a comparison basis with the D80, because I believe that is what you have? And if not, well, hopefully this is still helpful for you...
The D300's body is absolutely, hands down, a big upgrade over the D80. The D80 has a good body, but the D300 just blows it out of the water. The D300 is rugged, very well-sealed, and it's simply more comfortable to hold. And it also balances better with longer or heavier lenses, by a lot. The body also has better gripping material, and my hands down sweat as much when I hold the D300 as when I hold the D80.
The screen on the D300 is actually worth the upgrade alone, to be completely honest. I don't use live-view a lot, but it is definitely a really nice feature, and I'm sure I'll use it more when I start getting heavy into portraiture that isn't self-portraiture. But the screen, just when reviewing images, is amazing. Crystal clear, bright, vivid, beautiful, seriously, if you haven't seen the D300's screen in person, you haven't seen its greatness, it's the best screen I've ever seen on a camera. By far.
If you do any shooting with sports, the D300 will be a big, big, big step up from the D80. Throw on an MB-D10 battery grip, which I highly recommend, and you're golden. But without it, you're golden. The FPS on the D300 without the grip is 6fps, and with it, 8fps, and that is huge when shooting sports. Pump up the ISO to 1250, which results in a basically low-ISO image, and I can shoot at 1/640 in a hockey arena, shooting TIFF, Active D-Lighting on High, Noise reduction on, I can still get six shots in the time it takes a player to take a slap shot. If I took the shot with JPEG Fine, Active D-Lighting Off, and noise reduction off, I'd probably be able to shoot eight or nine. It's a very fast camera.
More about that ISO stuff, since that's pretty important...the D300 blows the D80 out of the water. Completely out of the water. You could shoot at ISO 1250, or 1600 with the D300 all day and not have images that were overwhelmed with noise, you could shoot at ISO 3200 if you felt like it, and the noise is certainly manageable. And if you felt like it, pump it up to ISO Hi.1.0 (6400 equiv.) and you'd be able to save the shot in post-processing. The ISO performance is at least, at least, twice as good as the D80's in my opinion, and for some shooters, that alone would justify the upgrade.
Let's see, what else is there to touch on? Commander mode is in there, but I think that's in the D80 too, that's a great feature. The D300 works with some lenses the D80 doesn't it, but they're really old ones, so that might not be much of a difference. Oh, the button layout is better on the D300, it's way faster to change just about every option on the D300, so if you switch WB, or ISO on the go, the D300 will be about one to three steps faster in that regard, which might not seem like a big deal, but once you go to the D300, you'll feel like any less of a camera is simply holding you back HAHA.
So, to sum it all up, the D300 is absolutely, hands-down, in my honest opinion, completely, 100%, worth the upgrade. You will not look back, unless you get a defect. But if you get a good one on the first try, like I did, you will not regret it, at all. Seriously, go for it. It's totally worth it.
If you have any more specific questions on the D300, please feel free to ask me, I'll answer anything you want to know the best I can. And will certainly look something up in manual if for some reason I don't know. Hope this helped.