With the Core 2 Duo, Intel has done an about face in how their processors work.  Gone is the Pentium's Netburst technology, replaced with a more efficient and powerful design.

Reviews of their new processor have begun springing up all over the internet, and the results have been impressive.  Most of the reviews deal with the expensive (~ $1,000) Core 2 Extreme EX6800 processor (their fastest initial Core 2 processor), and the 'power gamer' Core 2 Duo E6700 (~$530) and E6600 (~ $320), the but a few reviews also have results for the low end E6300 (~ $165).

Below are links to reviews, and which Core 2 processors are included in each review:

AnandTech (E6300, E6600, E6700, and EX6800)
The Tech Report (E6600, E6700, and EX6800)
ExtremeTech (E6300, E6600, E6700, and EX6800)
Hot Hardware (E6700 and EX6800)
X-Bit Labs (E6300)
FiringSquad (E6700 and EX6800)
Hardware Secrets (E6700 and EX6800)
Sharkey Extreme (E6600, E6700, and EX6800)


A few quotes from the reviews:

After years of wandering in the wilderness, Intel has recaptured the desktop CPU performance title in dramatic fashion. Both the Core 2 Extreme X6800 and the Core 2 Duo E6700 easily outperform the Athlon 64 FX-62 across a range of applications—and the E6600 is right in the hunt, as well. Not only that, but the Core 2 processors showed no real weaknesses in our performance tests.- The Tech Report

Intel's Core 2 Duo and Core 2 Extreme are almost here, and they seem to be everything Intel promised and then some.  The Core 2's 4-issue core, shorter pipeline, Smart Memory Access and Advanced Smart Cache technologies make Intel the performance leader once again.  It was a tough few years for Intel, as AMD's Athlon 64, FX, and X2 processors outperformed their products almost across the board.  But Intel isn't playing second fiddle to AMD anymore.  Make no mistake, the Core 2 Duo and Core 2 Extreme are very real, and their performance is undeniable. - Hot Hardware

Intel's Core 2 Extreme X6800 didn't lose a single benchmark in our comparison, not a single one. In many cases, the $183 Core 2 Duo E6300 actually outperformed Intel's previous champ: the Pentium Extreme Edition 965. In one day, Intel has made its entire Pentium D lineup of processors obsolete. Intel's Core 2 processors offer the sort of next-generation micro-architecture performance leap that we honestly haven't seen from Intel since the introduction of the P6.

Compared to AMD's Athlon 64 X2 the situation gets a lot more competitive, but AMD still doesn't stand a chance. The Core 2 Extreme X6800, Core 2 Duo E6700 and E6600 were pretty consistently in the top 3 or 4 spots in each benchmark, with the E6600 offering better performance than AMD's FX-62 flagship in the vast majority of benchmarks. Another way of looking at it is that Intel's Core 2 Duo E6600 is effectively a $316 FX-62, which doesn't sound bad at all.- AnandTech

The launch of the Core 2 processor line has hit the market with a bang, and offers up an incredible combination of performance and value, coupled with low heat and power specifications. These processors are so good, that it's difficult to highlight any real negatives. The Core 2 Extreme and Duo processors offer record-breaking performance, industry leading power specs, and are priced so that virtually anyone can afford one. It has been a long time since we have seen a processor walk over the competition like this, and we should all thank AMD for bringing out the very best from Intel, as well as proving that competition does indeed work.- Sharkey Extreme