I think Erica is absolutely amazing. In my opinion, she's the best Lois Lane to date.
And that's saying a lot, because I remember loving Teri Hatcher as Lois when I was younger. But Erica really brought the character to life. She managed to waltz into the series in season 4 and steal the show one season, one episode at a time. And I imagine that's hard to do, especially with fan favorite Lana on the scene. Trust me, I know because I was a hard-core Clana(that's short for Clark and Lana) fan, until Lois came into the picture.
I could say that it's just that Lois is an awesome character and Erica Durance just happened to be acting her out, but I'd be lying. Erica Durance is the perfect example that the actor (or in her case actress) makes the role. She succeeded in making Lois strong, smart, courageous, funny (sarcastic), confident, sweet and vulnerable all at once. She also made Lois loud, bossy, insulting and annoying at least half the time, but she owned it and made those characteristics charming and indispensable for Lois' character.
Lois was the only one besides Oliver who could handle Clark and wasn't afraid to tell him how things were. If he was awesome, she told him, but if she didn't like his behavior, she called him on it and he listened to her. She gave Clark a lot of tough love over the seasons, but she could also be really sweet and a shoulder to cry on when he needed one the most. While Clark was used to being in control, she nipped that behavior in the bud from the start, bossing Clark around instead. (I think that at first Clark condoned it because she was older and hard to handle, but that at some point he started to like someone else being in control for a change).
Clark didn't need another person to worship at his altar, or for him to worship at someone's altar. He needed someone who understood him, trusted him and believed in him not because he was the savior mankind had been waiting for, but because he was Clark, a simple, flawed person, who happened to have the potential to be something greater with the right guidance. He needed someone to be his strength, when everyone expected him to be strong for himself. He needed an equal. And Erica showed in her every performance that Lois was Clark's equal. She shared the burden of Clark's destiny early on, without even knowing it, simply by being there and being Lois.
Erica owned Lois and she played her with style. She made Lois' character believable, real, relatable and absolutely lovable. In every way she made Lois' character better than I ever thought it could've been and as a result, she made Smallville a better show.
I've watched other productions with Erica Durance. The Butterfly Effect 2 is another one of my favorites. And I think she was just as amazing in that movie.
I think Erica Durance does not get enough credit. How this woman hasn't managed to land her own show or another lead role in a show is a complete mystery to me.