They can me amazing healers with respectable damage if they go a magic caster type, from dawn's wrath they get a fire bomb which can be AOE, and also a semi-nuke (solar flare) which can be morphed to cast instant.
All that with also a resto tree that doesn't need to be stuck by using a resto staff, meaning you can easily level up with heals available without sacrificing any damage.
They also get access to an amazing morphed CC, javelin toss, which with magicka hits like a truck.
Their only downside is mana management, and before launch zos decided to give them 0 mana regen passives, if u noticed this beta they had restoring spirit which gave some mana back for each spell cast, well no more, thats gone now into something so useless i already forgot about it .
Still mana can be managed, and no other class will have that "OH SH***" heal.
They can be tanks, although their aoe damage will be restricted to radial sweep, unlike a dragon knight who keeps everyone on the ground, still a respectable, self healing tank is nothing to look away from
DPS wise they also don't get back at all, dual wield, 2h, bow, everything works, with bow medium armor sounds the better path, but you can always level up both medium/light or medium/heavy depending on your secondary roll if you plan on one, with bow I do recommend to level up with at least 2 heavy pieces on you so the tree levels fairly well with you, so you can later go 2h for the CC it offers and maybe even change to more heavy oriented overall.
Literally they are the jack of all trades, still you can't reach every tree for every role, some careful thinking is required, and it comes with some setbacks mostly regarding mana, for all paths taken.