I bought this show for my wife, because she absolutely loves it. I enjoy it as well, however, I can see that it's not for everyone and can be a bit cheesy. The overall plot of the main character Nick learning that he is a Grimm and can see mystical creatures called Wessen, and his learning what his role should be, is quite interesting. Where the first season falls short however, is in its "monster of the week" style of episodes.
Like many shows, it does improve with the second season. So, if you are a fan of the show, you will surely want this season, even if it isn't the best, but if you weren't a big fan of the first season, keep watching and definitely pick up season 2 when it comes out.