Speaker driver sizes - pros and cons

Depends on what brand and composition of the drivers used as well as the xover and cabinet design.So size of the drivers are a very small part of a total design.

I've had a pair of Silverline Prelude small towers for years, and they're punchy, coherent, sweet sounding things. 2 3.75" (!) woofers and a 1" tweeter in each rear ported cab, all drivers are magnesium/aluminum including the tweeter...I recently replaced these (haven't sold 'em yet...hard to part with them) with Klipsch Heresy IIIs that sound remarkably similar in the sense that they're clean and coherent, a squat and fat 3 way with 2 titanium driven horns and 12" woofer. They don't play as low as the Preludes, but I've used 2 REL subs with both designs so no problemo, and I bought the Heresy IIIs simply to have more efficiency available. Utterly different designs, both do music amazingly well. Note that paper cones show up in some form or other in many high end designs (Wilson for example) as do soft dome tweeters, and they respond to what the designer wants to hear...my metal dome Preludes were never harsh or metalic sounding, and neither are the titanium drivers in the Heresys. 12" paper woofers...who knew?

Here are typical differences. These are not cast in stone.
Advantage of small driver:
better frequency extension in the treble region
smoother midrange response
tighter focus in imaging & soundstage
Easier to use in any size room (smaller)

Advantages of larger driver:
Moves more air for more impact in midrange and bottom frequencies, large rich images.
Better excursion limits for better power handling
Normally produces large rich soundstage
Normally higher sensitivity

Disadvantages of small driver:
Less power handling
Cannot portray the large orchestral experience as well
Limited Frequency response in bass
Normally less sensitivity

Disadvantages of larger driver:
Normally not near the treble frequency extension
Normally not as clean in the midrange
Normally requires a much larger cabinet
Beaming is often a problem

timlub, you forgot to mention that smaller drivers are usually faster than larger drivers - less mass to push and pull back and forth.

Also, I disagree that small speakers can't reproduce a large orchestral experience.  You just need more than one; active and range limited or passive.

After years of owning, testing and listening to all types and sized of speakers and main drivers from 2"-15", I prefer a single driver (or dual as mentioned above) no larger than 8' and coupled via high level output to a pair of very good subs.  This combo seems to work best for me, but I should also mention that I am driving tube amps ranging from 1Wpc SETS to 50Wpc push-pull.
 

@br3098 
Hi br3098.... I didn't forget to mention that at all.... I don't believe it.  I've heard 15 inch woofers that are very fast and dynamic.  Mass vs Motor tell the story.  As long as you have enough motor structure to push the mass speed is not an issue.  The problem lies when you start having too much motor. Yet another subject.