Kinda depends on what you feel like you are missing. If you want a vanilla android experience in a phone with a smaller footprint then it's not a bad purchase. Especially since the Nexus 4 is relatively inexpensive for an unlocked device. However, the Note 2 has a lot of great features (larger screen, touchwiz additions, removable battery, etc) that you might miss if you switch over. So unless you've been really jonesing for a vanilla android experience and more assured Android updates, don't really know if the Nexus 4 is an upgrade.
If you're waiting for I/O just in case there will be some great device it's a tough choice. Personally, unless I know something is available in a couple of weeks, when I'm ready to buy a new toy, I just buy what is currently out, that I know I'll love. That's how it was when I bought my Nexus 7 and Nexus 4. No regrets.
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