I am surprised no one posts these video links yet. (Can't post links yet, just put www in front of the youtube)
Elementalist's Skills and Traits: youtube/watch?v=ZvKzw_dLoz4&feature=plcp&context=C30a55a8UDOEgsToPDskLKVNuuVH-rrPZqXR9fqD3e
Elementalist's Skills (including conjure weapons' skills): youtube/watch?v=E3tpzyXK3CU&list=UUoT3pUXscJUm6Hbj29edYyQ&index=8&feature=plcp
For conjuring weapons skills, there is one weapon for each elements: Fire Axe, Frost Bow, Lightning Hammer, and Earth Shield (and Love. Go captain Planet!!! :P) The weapons seem to last for 15 skills usage.
Fire Axe seems to be short to medium range AoE weapons with an AoE charge. Almost all skills are AoE damage skills.
Frost Bow is more of a long range control/support weapons, with the first skill that deal damages and heal, while others cause some kind of conditions (or creating ice wall).
Lightning Hammer looks like a melee weapons with a wide swing and melee AoE skills such as Static Field (same skill from staff but in this case it is cast with yourself as a center). It also has a leap ability like warrior or guardian too. Talking about Thor's hammer!!!
Earth Shield pretty much centers around defensive ability (such as skill five which make you block all attacks). But it still has some offensive control ability (such as throwing shield to cripple enemies in a line). It basically turn you into a Captain America :P
So it seems that Elementalist with the conjure weapons retain the position of the profession with highest amount of skills available and trumps the Engineer in that regard :P
There are a couple of things I would like to point out. The first is that the elemental summoning skills will not recharge unless your elemental is killed. So you have to wait 45 seconds after your elemental dies before you can summon another. So you might want to put that slot in other skill instead. I would say Arcane Shield might be a better skill slot for that if you want survivability because it give you three blocks of incoming attacks.
Another thing is that I am pretty confident that "Written in Stone" will undergo a redesign or some sort of change. The current form of this trait is not so creative and boring in term of game play. Signets are designed to make players choose to activate for an immediate effect or use passive effects on it. Written in Stone just destroy this dilemma and I do not think that it is a good thing.
I would say that is not a big of a problem. They might be able to support quite better than, says Warrior or Thief, but they cannot heal through all the damages dealt by npcs or other players. And normally Elementalists would have access to at most three heal skills (staff), which does not heal that much at all.
Water attunement deals less damage and heal for very little because it is more of a support/control element. Fire is a pure damage element; Air is pretty much damage and control (and a little bit of support in Staff); Earth is more of a control/survival. So playing water as main element would mean you are going to support and control more than dealing damage.
There are a couple of good videos for mesmers. Check these out:
youtube/watch?v=O5ATXO_mSsY&feature=plcp&context=C36eda21UDOEgsToPDskLc252mBOjhojeK-UwM5Fhm - Mesmer's skills and traits.
youtube/watch?v=2kYALiuab4c&list=UUoT3pUXscJUm6Hbj29edYyQ&index=4&feature=plcp - Mesmer's skills
It also depends on how a player put points in to traits too. If a player max out the water trait line, then he would be better in support than deal damage. But that does not mean the Elementalist is the only class that can support. Engineer putting traits into a support line can support as good as the Elementalists. Same goes to the Guardian or even Necromancer. Hell, if you look at the Warrior's support traits you can even say that Warrior can be a really good reviver!