Its a great show with really good action and plot. The actor playing the character of Flash is very talented and the role suits him perfectly.
The first three seasons were awesome and Thawn is one of the best villains I have ever experienced out of all the TV shows I have watched till now.
Saying all these I also want to point out some of the drawbacks the show is having which started to become more visible after season 3. It seems like the scriptwriters lost their interest on the show from season 4. The plots were weak and they sort of gave everyone the superhero status. Iris is a great character and suits with her role, I do not see the point of making her the super-hero. The show is going downhill since then, I hope the scriptwriters give some more time on the show and get back on track.