03/14/2008 at 01:45 PM EDT
completed two days of filming on TV's How I Met Your Mother
, receiving praise from the sitcom's cast for her attitude and comic skills.
"There was not an ounce of the dark side that we've all read so much about," star Neil Patrick Harris, 34, said Thursday night at a West Hollywood party for the show.
In the episode, which will air March 24, Spears plays a receptionist
at a dermatologist's office, and she falls for one of the show's main characters, played by Josh Radnor.
Spears, 26, shot her scenes Wednesday and Thursday.
"She was hilarious in the table-read, and I got to see her do the run-through as well, and she was great," cast member Jason Segel said at the Jameson Irish Whiskey St. Patrick's Day party. "She was great and lovely and couldn't be sweeter."
Added cast member Alyson Hannigan: "You can still kill a joke if you don't have comic timing, and she's not killing them. She knows how to deliver a joke. She's got good comic skills."