I just bought one a few weeks past to replace my broken one. I got it plus the official dock, a usb dock and several cases for £250. A steal and it's still one great phone 
It is not only the core itself, the common glue logic around it gets more complicated and potentially power hungry too. The question is how much and if it can be compensated by the potential dual core power savings.There is another feature of these new dual-core chips, is that one of the cores can be toggled on demand. No sense in burning both cores if you're just checking e-mail or syncing calendars/social statuses, but a resource-hungry media app or a 3D game for example would spin up that 2nd core.
Good to hear that cuz I have the same feeling about my n1. Whatever phones I got before I just wanna sold it right about 2 weeks I got it. But I've been keeping my n1 for a year and I just have a connection with it. Even though lots of new phones have been out and dual cores are just nowhere any farther. I'm considering buying a new phone but theres just something about the n1 makes me wanna keep it forever. The g2 on the other hand isn't a bad one either. My wife got one and she loves it, I love it too. Don't even under look the 800 mhz. It's a lot of power with that chip clocked at that number. I'd say you suggest your friend to wait for a dual core before h1 he falls in love with the n1 like we do.Bought the desire hd a few months back but still im on my n1... dhd cant match the speed n pure google experience... luv the n1 sooo much i'll go so far as to say its the best phone i have ever owned...
Great feedback, thanks.For me personally I wouldn't trade my nexus one for any current market offerings. But with upcoming phones, I really can't recommend it either. As in, if I didn't have my nexus one and needed a phone today I would not buy it. More than likely I would buy a cheap pre-paid phone throw my sim in it and wait for the new phones.
Right now is a very tough time to think about getting a phone. While the current selection of phones available is pretty good, realistically they are only slight upgrades from the nexus one. The upcoming models from CES and soon to be announced ones at MWC are looking/going to be pretty sweet and definite steps up. And in my opinion those phones are going to give your friend more longevity and bang for his buck than buying the nexus which is finally starting to fall behind the times technology wise.
But if he doesn't need to be on the cutting edge of technology, the nexus one is still a very capable phone. And luckily it seems like the devs are still putting out good roms so if he is cool with rooting (which everyone should on an android phone) the phone will not let you down.