Nexus One is a good phone (except battery life, it sucks. I have to charge the phone twice a day with my usage), no doubt but Android still has a long way to go. It has two serious problems:
1. It is more orientated towards being an OS and it leaves many important features of a Phone. Google forgot that Android is not a full fledged Phone OS yet and N1 is a phone first. See this thread of mine for some of the missing features in only the Stock Dialer!!...
Issue 7023 - android - Stock Contact/Dialer Improvements/Enhancements/Bug Fixes - Project Hosting on Google Code
2. Google is damn slow in fixing issues and replying to old ones. That is a common problem and you can go to Google Code's Android Issue list to see what I mean. Minor issues, which are more than a year old, are still open and are present in 2.1!! I didn't expected Google to be such a crawler. Sad.
I know that we can Flash the phone with some ROMs to get some of that functionality, but it is like saying, "Buy a car and install wheels and a steering to get it working". If I am buying a phone, it should do all things a phone is expected to do in all it's factory glory.
Google needs to get it's act straight. A Phone OS and a Tablet OS are different. Google is trying to get two birds with one stone. I don't think that will work. Atleast it is not working now. And Android is completely not ready for Enterprise customers yet.
As for me, I am using two phones so my problem with Nexus One have a backup solution. Otherwise, I would have certainly switched my Nexus One by now.
I like Android a lot but it needs a lot of work. I hope Google wakes up sooner than later.