If you like supporting your party members then this is the class and build for you. This build is not pure group PvE but it get the job done without any complaints from your party, which is useful for any MMORPG. This build is hard to kill because you will depend on Magic Barrier, so being debuffed is really, really bad.
PvE: If you can’t find a party, you’re better off finding solo quests and live off of those. However, because of the nature of the build, you will do yourself a favor if you just find a consistent party. The life of a healer isn’t very hard because all you need to do is keep track of life totals. You will be pmed like mad to join parties and you can get into some great boss farming parties and get some really great gears or items for synthesis.
PvP: Frankly, this build isn’t really build for one-on-one fights. Sure, you’re tough as nails with Magic Barrier and some damage reduction spells but you won’t be able to deal enough DoT damage and DPS to kill many people unless they screwed their build up. Priests really shine in group pvp to keep those tanks and DPS guys alive. The main focus in group pvp is to keep people alive.