It does need more stuff

It needs people and flowers

I think you need a new coffee table situation.....the ottomans look too much like the couch, so there's no variation. A coffee table out of a different type of material, such as wood, glass, metal in a lighter color. And maybe an area rug with some pattern in the couch area as well.

[houzz=]

what do you think is missing,looks like a nice room alreday,but maybe a little more color on the walls or curtains with a print next to the ones you already have or different trays on the ottoman or one wall with a feature wallpaper???

[houzz=]

coffee table example with wood and metal

or here are some that are red....maybe not bright red, but red with a black glaze or wash on them. but I really think if you change the table and put a patterned rug underneath, you'll get the look you are after.

One other thing that may be cool, is to put mirror inside the book shelves or a fun patterned wallpaper.

the painting over the couch appears to have more orange and yellow in it than red. If so, changing out the pillows and drapery panels to bring in the orange and yellow would be a room brightener. Adding a patterned area rug under the couch legs and extending beyond the ottomons would be a lovely way to add the orange and break up the sea of brown. Nice furniture and nicely arranged!

Replace panels on window, look cheap. Replace with a print, try white with yellow, or teal, touquose. Replace pillows with same color. Red hard to work with. On selves behind sofa remove all. And replace with silk plants. And candles in white. Can you paint? If so a soft gray would warm the room. Get much taller 2 feet. Put on end table, add a nice silver bowl. Don't clutter. Replace ottomans with color ones or try zebra, always fun. Move brown ottomans to another part of room for seating. I like pic. Could use colors from that in panels. Looks like greens, yellows .

No need to put things on ottomans.

Add a tall plant bamboo or palm can be silk. Put by end table and chair. Can you pull sectional out from corner. Away from slider about a foot. All furn pushed into corner looks too heavy. Then replace floor lamp with something tall and different . Ck Ikea they some fun lites.

No fake flowers. Putting plants and pots with flower on desk would give room more interest too. Don't forget about outside.

In pic yr walls look gray. If so keep.

Also never again buy furn that matches. That is biggest problem. When people say room doesn't come together. Matching furn is usually why. That black chair, can it be moved to another part of room? If so replace with fabric one in a print. Pick your accent color ( not red). And use that. In a small room use 1 or 2 accents colors otherwise rooms looks too busy.

I agree with Joan replace end table with glass to lighten room.

In above comment I meant to say replace lamp with tall 2 feet lamp, on end table.

See carol comments picture the panels with that type of print is what I meant. Those are orange which would work. Or any color you choose. Try bed & bath.

Here are a few SIMPLE and CHEAP fixes that will likely make a big difference:
add a large bushy floor plan at the end of the couch/in front of the window. plants lighten up a room and add a bright green that gives energy. the plant needs to be of appropriate scale - you'll know when you get it right. placing something round here will also break the hard lines in that part of the room - when you add a soft transition to a 90 degree corner/angle it makes a huge difference.
place a cascading plant (silk) on the top shelf where the photos are - put it on right side and let it cascade over ledge - do this to break the lines in that corner and add brighten corner up. go with something verigated as leaves will have white in them)
brak up your books as well...see picture i attached to see waht im getting at. you can use anything interesting to hold books in place, or turn them on their side. dont line things up vertically.
and lastly...you need something interesting on your coffee table - it needs to be the right size too. books are easy and allow you to have 'levels' to play with. see pic for an idea.

I would take out the curtain and put Venetian blinds instead, split the sofas and armchairs and put them in the middle of the room. Am interesting rug would help too. Ditto big plant.