I had side effects from Asacol, so I didn't take it for more than a couple days. I have had no problems with Lialda. However, I am also on Remicade, and I'm barely hanging on. I do notice things are worse though when I forget to take the Lialda (forgot a couple weekends ago - both sat and sunday and paid for it on Monday!).
Good luck with it! Go to their website, and you can print off a coupon for a free 30 day supply.
Diagnosed w/IBS: Oct. 2006
Diagnosed w/UC: Jan. 2007 (proctitis), July 2008 (pancolitis)
Canasa (helped the first flare when it was just proctitis); Rowasa enemas (did not help as the following colonoscopy confirmed pancolitis); Lialda ( 2 pills in the morning, 2 pills in the evening, soon to be 2 pills in the morning only once I'm off steriods); Prednisone; Protonix (only took while on prednisone); Remicade infusions, started at 5mg/kg, increased in March to 7.5mg/kg (started Aug 2008 - 6 infusions so far, next infusion on 4/30 continuing every 8 weeks); Zyrtec-D (for allergies); Toprol (a generic form, 25 mg, for a rapid heart rate)
Supplements: Women's One-a-day multi-vitamin; Super B-complex
w/vitamin C, Iron supplements, Omega-3 Fish Oil (coated, not sure how much except one soft-gel daily), Aloe Vera supplement (two daily), Acidopholis
Diet: Spinach and Sunflower seed butter diet (starting 3/21/09)
Current Status: Reached remission for a few weeks in October 2008, but symptoms returned after I allowed myself to enjoy wine again.... gave up wine and have not been in full remission again yet.