My wife (Stage IV Adenocarcinoma) is currently on Alimta and Tarceva. The doctor says his goal for this regimen is stability (not reduction) and so far its working. She's been on Alimta since the fall.
In general the Alimta is pretty tolerable compared to her original regimen of CarboPlatin, Taxol, and Avastin. The worst side effect is a rash that flares up after treatment but subsides within a week. The doctor was able to treat it with Acutain (a prescription med for acne) but her liver enzymes started to get elevated from the Acutain so they stopped it. Currently they are treating the rash (some what successfully) with some topical creams.
I hope that helps. Good Luck.