I still have my Clip 2 so I can compare it side by side with the new Clip 3. My reasoning for purchasing the Clip 3 was for its top mounted controls which are a much needed addition, plus the elimination of the built in auxiliary cord in favor of a protected auxiliary socket. I rarely used the built in auxiliary cord so removing it was a smart move at least in my opinion.
The new clip design isn't as big as the old model but I haven't had any issues with it in use.
The speaker phone function is also just as good as the old one. JBL uses noise and echo canceling mics on their speakers which is great, my GF hasn't asked me to repeat myself once. Battery life is also advertised as being two hours longer which is great, but I never had an issue with battery life on my Clip 2. Its just nice to know I can go longer between charges.
Audio wise JBL has listed the same specs for the Clip 3. The speaker is still at 3 watts and has the same frequency response. But in comparing them side by side the Clip 3 has more bottom end, more pronounced and fuller sounding mids and the highs seem to have been adjusted to match up with the mids and lows. Plus at higher volumes the Clip 3 doesn't seem to limit its audio profile as much as the Clip 2 does, but both speakers get just as loud which is fine since the Clip 2 could get pretty loud for its size. The differences aren't like night and day but you notice them right away when switching between the Clip 2 and Clip 3.
BT range is about equal between them which is great on both speakers, its about 60 feet if I had to guess. Both speakers also have a solid connection.
So overall I think the Clip 3 is a worth while upgrade over the Clip 2. The new button location was a big reason for me, but the unexpected bump in audio quality was a nice surprise.