Quake Live revives classical deathmatch game play, makes it better and offers it for free.
I've been playing deathmatch first-person shooter games going back to the original Doom until about the first Call of Duty game. The problem with Quake 3 was that the skill level between players made the experience difficult to enjoy at times. Quake Live's automated skill matching system largely mitigates this problem. The deathmatch gameplay shows the benefit of years of player play testing feedback and is tight, balanced generally improved over its Quake 3 forebear. As expected the game runs quite well on virtually any modern PC. Another benefit is if you live near one of the several Quake Live server hubs, like San Francisco, the network latency is near non-existent. There is also a robust "Xbox Live" like achievement system and robust match record keeping in the web interface that is nice for stats junkies. Quake Live also will tell you if any of your Quake Live friends are currently playing and with a single click allows you to jump into the map he or she is playing in. One of the biggest positives for Quake Live is that the game is completely free. id Software is attempting to make money by selling in game advertising and this would be a potential negative but so far the ads are by and large seamlessly integrated into the arenas and do not detract from the gameplay. The pacing of Quake Live can be considered a positive or a negative depending on one's personal prefence. Personally, I like the furiously fast paced action but it might be a turn off for others that don't enjoy high intesity frag fests. Matches are always over in 15 minutes or less.
Negatives
The drawbacks aren't prohibitive but need to be mentioned. The game runs in a web browser and doesn't runs nearly as fast as the original Quake 3. This can pose a bit of a performance problem for laptops without dedicated graphics hardware. I've read that netbooks need have Quake Live configuration tweaking to run at even playable frame rates. Another limitation is that there are no private servers. Meaning if you have a group of your friends that want to play each other, you and your friends can't play either other without other random players potentially joining in. Also all the game types, maps and game settings are fixed. So, no player created mods or content is allowed. Finally, the maps are nicely done but a bit dated looking given this is a 9 year old game at its core. Modern first-person shooters make the Quake Live engine look dated by comparison. Although not as much as one might expect. The player characters are by far the most dated looking but thankfully one is rarely focusing on player model details while playing.
Summary
The gameplay is tuned and the game is free as in beer. It's hard not to be sucked into the visceral pleasure of well done deathmatch mayhem.
Overall, I give it a 9.0 out of 10.