1) What Camera do you use?
Pentax K20D with a DA* 16-50/f2.8 and DA* 50-135/f2.8
Pentax Spotmatic SP with SMC Takumar 50/f1.4 (for B&W)
2) Why did you buy it?
After a heap of research it seemed like the best fit for my needs. Nikon D300 didn't fit very well ergonomically, Canon 40d/50d aren't weathersealed, and I felt that K20D image quality was better than the Canon's and Sony's A700. I was very tempted by the Olympus E-3, but in the end i just couldn't afford it... I managed to get the K20D & 16-50/f2.8 combo fo the same price as a D300 or E-3 body alone
I was also impressed with Pentax's made-for-digital lenses.
3) What do you like about it?
The build quality and weathersealing are great, i've had it in some pretty nasty weather and it's never missed a beat. It has some really clever little details, like the 'hyper' mode and green button, that are incredibly useful in real life shooting conditions. Image quality is excellent, and 14.6mp lets you blow prints up a fair bit. High ISO performance is excellent for such a high-res sensor. Both the DA* lenses (particularly the 50-135) are great, especially considering their price compared to similar Canikon glass.
3.1) What DON'T you like about it?
Auto Focus struggles in low light and there isn't a focus assist lamp, ie. Nikon. Metering can be fooled in tricky conditions, and will pretty much always over-expose dark scenes. The low-res screen makes it difficult to check image sharpness.
4) (update) at TasAdam's request - what gear do you carry?
Usually only carry the K20D, 16-50 and 8gb card. I can get 6-700 shots out of one charge so i haven't had need for an extra battery yet. If i'm feeling creative i'll take the 50-135 and a Rocket Blower as well
Long-term, i'll wait till the new Pentax K-7 comes out and see if it's as impressive as some people have been saying. If not, i'll seriously consider changing to Olympus' E-system and their wnderful Zuiko Digital lenses