Restaurants are a lot like relationships. When new, they’re all fireworks and surprises, plus a delicious sense of wonder at the possibilities ahead. As they mature, familiarity replaces fireworks, and – if you’re lucky – steadiness stands in for surprises. I thought a lot about that last weekend at Street and Co., the venerable Portland restaurant that opened in the Old Port in 1989. A visit on its 25th anniversary seemed an ideal time to find out how the place was faring.

Street and Co. (named for owner Dana Street, who also co-owns Fore Street a few blocks to the east) still bills itself as a restaurant that spotlights “very fresh seafood,” and it does that exceedingly well. The constantly changing menu (updated daily) is filled with fresh local fish and shellfish, including succulent Basket Island oysters, Maine crabmeat and lobster delivered on demand by Mike Libby, a lobsterman who operates out of Portland.

The place continues to be popular. Certainly the noise level last Saturday suggested that diners were enjoying themselves. Street and Co. has always been known for its din, and that hasn’t changed, even as the restaurant grew to occupy more space on Wharf Street. If “pleasant buzz” is your version of happiness, you’ll have to go elsewhere. Raised voices are the norm here.

But amid the crowds and the clatter, and the compelling drama of the open kitchen, something’s missing. It’s that steadiness – consistency – from a kitchen that can produce impeccable Mediterranean-centric dishes but sometimes falls short, and from a front-of-house staff that knows all about hospitality but occasionally appears too bushed or too busy to extend it.

Street and Co. won over a generation of Portland diners with a passion for excellence early on. Twenty-five years later, I wondered, where has the love gone?

Take our dinner experience last weekend. The place was bustling and we had to wait in line to be seated, but a polite hostess finally guided us to seats near the front window. The dining room is expansive and attractive. Tables are either made of soapstone or clad with copper so that waitstaff can set down what they call “sizzling pans” plucked from the stove and delivered to customers with a reassuring oven mitt over the handle. The beamed ceiling is low and hung with dried herbs and peppers, and the antique wooden floorboards, all salvaged from historic barns, are wonderfully worn.

The kitchen showed skill with appetizers, a simple platter of oysters freshly shucked and swimming in their own intensely briny liquor, and an enormous bowl of Bangs Island mussels simmered in heaps of garlic and white wine. With good mussels, conversation at the table should stop, and ours did. We were too busy scooping and dunking and slurping to banter. Not only were the rope-grown mussels nicely cooked – moist and tender and garlicky – they were steeped in butter, a credit to Dana Street’s physician father who developed the recipe. (His specialty, apparently, was not cardiology.)

Two of the entrees that followed were also tasty: sole Francaise ($28.95) and scallops in Pernod and cream ($30.95). The sole is a signature dish that has been on the menu since the restaurant opened. Lightly floured, dipped in egg, then sautéed quickly in brown butter, each filet is finished with an enthusiastic squeeze of lemon juice that blends with the butter to create a rich, bright-tasting sauce. It’s easy to see why one frequent visitor told his waitress, “I don’t need to look at the menu. I’m having the sole.”

The scallops were also fine: plump and sweet, sautéed with mushroom caps and finished with a splash of the distinctive anise-tasting liqueur that marries so well with shellfish. Dana Street says he’s thought about replacing this dish with something “less Brittany and more Galicia,” but his customers would be disappointed.

Which is precisely how I felt about the rest of dinner. Fisherman’s stew ($27.95) should have been excellent. It was filled with fresh mussels, clams, shrimp and swordfish, but instead of being intense and flavorful, the broth was bland and the shellfish tasteless. I took some bread, drank some water and dug back in, thinking that palate cleansing would help. No such luck. This stew was insipid, even with a dollop of aioli on top. (A friend turned to me and asked, “What’s the point?”) So was the swordfish, a small steak coated with spice and blackened in a hot pan. Where was the flavor? And where was the spice? Though the seasoning was sparing, the price was not: At $29.95 this entrée was an expensive letdown.

Desserts were uneven as well. Bourbon pecan pie ($7) was marvelously rich and nutty, but the panna cotta ($7) was uninspired, even with a ribbon of berry sauce over the top. I tried to hail our waitress to ask about that sauce, but she was stretched thin attending to nearby tables. In fact, we had a hard time finding her to ask for the check. It was eventually delivered with sincere apologies – and a description of what turned out to be currant compote.

Which brings me to the line we faced upon arrival. Street and Co. takes reservations for about two thirds of their tables, but deliberately saves others for walk-ins. It’s a smart strategy that keeps the tables full, encourages last-minute diners to stop by and proves convenient for tourists in the summer months. But the restaurant has enough experience with planning and crowd control to honor reservations in a timely manner. Customers, whether first-time visitors or loyal fans, don’t want to wait near the bar for 20 minutes while tables are cleared, not when they’ve confirmed a booking and left complete contact information. (And when a late seating translates to a late dinner and a late departure, front-of-house staff can make a positive last impression by standing up to say goodbye, instead of huddling at tables while tallying the night’s books.)

Street and Co. is a beautiful restaurant with an enviable history of success and an appealing mission statement on its website: “Local seafare. Mediterranean flavor. Rustic atmosphere … Welcome.” It should have all the elements in place to thrive for another 25 years. But Street’s team in the kitchen and out front will have to tap into some of the ardor and zeal that put his restaurant on the map in 1989.

Welcoming guests night after night may seem like more of the same for them. For us, each dinner’s a first date. We still want to be wooed.

James H. Schwartz has covered food, travel and architecture for The Washington Post, Downeast, Coastal Living and Southern Living magazines for more than 30 years. Long a commuter between Portland and Washington, D.C., he retired from his job as vice president at the National Trust for Historic Preservation in 2013 and relocated to Maine.