I've had my HTC Hero for around 6 months now, and on the most part, have really liked having it and enjoyed using it. Along with the Hero, I also have an iPhone on a business contract. After clearing my iPhone contract by a good £50 3 months in a row, I decided it was time to get a phone I could have for personal use and wouldn't destroy my bank account.
Initially I was a bit unsure of it. It seems almost as though HTC had tried to take the basics of the iPhone and put them into the Hero in a slightly different format, however after a couple of months use, it really began to grow on me. The interface is simple and easily customisable to suit individual needs, and the App Store-esqe 'Android Market' is loaded with mostly free and useful apps. I find the text interface very easy to use, and for those with the slightly larger fingers (like me) the phone can be turned sideways for a larger keyboard.
I think the main advantage the HTC has over the iPhone, however, is the battery life, which after near daily charging with the iPhone was amazing! If you have too many functions going on at the same time, the phone can be quite sluggish, but if Wi-Fi, Bluetooth etc. are off then the phone should run freely.

That's about all I have to comment on! It is an impressive phone, but may not be to everyone's liking!