After the initial "ooh shiny", probably not.
Improved battery life... fine okay, but currently I'm in the routine of just docking it after I get in from work. Not a problem.
Improved speakers... not bothered.
3G. A good addition but generally I only use EDGE to download my text emails and check facebook. It's fast enough for what I need. Yes, sitting there waiting for web pages to load brings back painful memories of 28k, but it's not exactly blazing fast on wifi either. A lot of the time taken is rendering the page too.
GPS. Now, a personal sat-nav is cool. However the times when I might NEED a GPS signal is when I'm out walking in the mountains, and I don't like taking expensive breakable gadgets with me. However, I can foresee 3rd party apps going mental with GPS, tracking your mates in realtime etc. I'd feel like Jack Bauer. GPS is something I'm actually excited about. Up-to-date weather forecast updated automatically. Traffic updates. Where is the nearest drinking hole/public toilet. An app that pulls cinema listings from a 1-mile radius. Tracking the b****** whole stole your iPhone 3G. The list is endless.
I'll wait for the iPhone v3.0 however.