Hi there - relatively new to these shores.
For what it's worth, my take on the "is it worth getting into Rift?" question is as follows:
- If you are currently playing WoW and mostly enjoying it: stick with WoW; Rift doesn't do anything differently enough to give up an mmo you still have fun with.
- If you are currently playing WoW and stopped enjoying it, but you used to enjoy it for prolonged periods: give Rift a go. If you had fun in WoW for a long time, but no longer, that suggests you like the fundamental formula of WoW but got burned out. Rift is similar enough, yet a little bit different.
- If you are very pvp-focused (e.g. you come from UO or DAoC): Rift is probably a waste of your time. There is no world pvp (in practice) and no RvR or objective-based world pvp. Just instanced pvp. And that doesn't even feature ranked guild v guild matches or anything like that. It isn't worth the sub for a pvp-er.
- If your mmo experience is with non-wow pve-centric games like EQ/EQII/FFXI/Vanguard and you hated those - try a free trial of WoW and Rift and go with whatever you like best (WoW by default; it is overall the better game atm). Either game is more accessible than the more hardcore pve games.
- If your mmo experience is with games like EQ/EQII/FFXI/Vanguard and you liked the commitment needed in these games: Rift will probably seem too "casual" to you. If you're desperate, go with WoW: there is more to do (Rift does offer a fairly impressive amount of content for a new game, but it doesn't get to compete against WoW in 2005. It competes with the behemoth that is WoW after 3 expansions.)
- If you are new to mmos: try a free trial of WoW and Rift and go with whatever you like best. Then wait for GW2 (just kidding

).