It seems like everything is kind of neutral with very few patterns or colors. Try adding pattern and color in things like blankets, throws (even though that one behind the couch looks really cozy), area rugs, decor for the coffee table, etc. Stuff that's affordable so you don't feel like you just broke the bank in case you don't like it!

It also looks dark, even with the natural light coming in from the right! Is there anywhere else you could add more lighting? A floor lamp or another table lamp, for example?

I would start with window panels with a pattern. Then a different wall color. I would do a different finish for the brick inside the mantle. Maybe a tile. (I would prefer to paint out or do something different with the fireplace wall but, most would scream at the prospect of painting brick)! Pretty, colorful accents and you are on your way!

I like it...it looks cozy! But as Lights says above, some color. Also more light!

I think people radically underestimate the power of proper lighting to take a room from average to good.

Depends also on what you want to change. Your sectional is large. Also the carpeting looks the exact same color as the sectional. That might be where you are thinking "blah" because it is just too much of the same with no contrast.

One or the other could be contrasting. If you are of the mind, perhaps replace the carpet with hardwood or laminate. Then a colorful rug would help provide some color and contrast. If you want to stick with carpet get something darker, or with some sculpting.

I think the room would be pretty with snow falling outside!

Good luck!

Thanks for the comments!! What about a ceiling light. Like a chandelier?

I think you can rearrange the furniture to make the room more open, and add brighter pieces to make the room less dark. Good space!