I'm going to have to disagree with god here. I have 4 gargoyles (necro/fencer/poisoner, mystic/thrower/imbuer (Baja), mystic/mage/imbuer (Atlantic), and thrower/peacemaker) and enjoy playing them all.
To complete a couple of his items:
1) Berserk does have a defense cost as mentioned, but it also offers faster swing speed and damage increase. That said, I don't go out of my way to get Berserk to activate.
2) Yes, Gargoyles are restricted in the weapons and armor they can use. I haven't seen it for myself, but I understand that some artifacts can get converted for Gargoyle use by GM craftsmen. Also, they can wear earrings; in fact, earrings are armor for them, replacing helmets/caps on other races. (Similarly, necklaces replace gorgets. Both earrings and necklaces are begging to be imbued with whatever properties the Gargoyle needs.)
3) Yes, Throwing has under- and over-throw penalties. For me, overcoming these is a matter of adapting playstyle. Neither of my Throwers bothers with Swordsmanship nor Parry. Just keep moving as necessary to stay an appropriate distance from your foes. These guys are only PvM; PvP would likely be problematic.
4) The reason Gargoyles are good with the Rising Colossus spell is this summon requires 5 control slots. The flying skill allows you to move fast and still have Colossus. Other races would have to sacrifice their ride.
4a) I don't know of any relationship between Gargoyles and greater dragons.
5) Obvious, but probably should be stated -- throwing weapons don't require ammunition. No running out of arrows or bolts.
In answer to Slayvite's concerns:
a) Throwing doesn't need Swords, unless you plan on standing in melee range while you fight. If you plan to do that, skip throwing and just take Swords.
b) Fencing does not reduce the melee-range penalty; only Swords does.
If you go with one warrior Gargoyle, I suggest fully embracing the new Styggian Abyss skills:
120: Throwing, Imbuing
110: Mysticism
100: Tactics, EvalInt, Meditate
60: Chivalry
If your skill cap is less than 720, you could drop Tactics to 90 and still keep Chivalry useable, aided by jewelry that adds to Chiv skill.
There are no New Haven accelerated skill gain quests for the new skills, but you can buy all three to 40 in Ter Mur. Until the latest patch, it was an extremely good idea to start with 50 Imbuing, but the skill gain restrictions regarding unraveling are gone. (It was a real pain to move from 40 to 50.1, which had been a magic number.) Now it doesn't matter which two you start at 49 with. I'd go with 49/49/2 on the three skills. You'll immediately buy the 2 skill up to 40, so you won't start out in too bad a shape whichever one you choose as lowest.