BISTRO DES CELESTINS is named for a contemplative order of Benedictine nuns, a group that presumably practices forgiveness, and for a sparkling Vichy water believed to settle the stomach. I can forgive the kitchen a lot for the saving grace of their first-rate french fries, but the service has been known to leave a sour taste behind.

When I first came to Washington, my neighborhood restaurant was a lovely little French place on the Senate side of the Hill called La Brasserie that belonged to former French Embassy maitre d' Raymond Campet. For more than a decade, Campet and his wife, Lynne, have run La Cote d'Or, a much-loved little Provencal/Basque-flavored outpost at the Falls Church end of Arlington, as a two-room establishment. But a few months ago, they decided to split the restaurant into two, turning the bar and front room into a bistro (making logical use of the partially exposed kitchen) and transforming the underutilized and slightly more formal back room into Cote d'Or.

The idea is great. These days, when cutting-edge French restaurants are playing the name-that-food game (is it pasta or squid?) and rapidly escalating from gold to platinum card prices, Celestins' menu seems old-fashioned indeed, and it's something of a relief. Croque-monsieur, crepes, moules et frites, clams casino and oysters on the half-shell, lamb steak . . . it's all just so comfy. What's discomforting is the bistro's -- or rather the staff's -- seeming confusion about its new split identity. Despite the more relaxed concept, it feels strained -- it doesn't feel so much like a family joint anymore. Service is sometimes pleasant, sometimes condescending, sometimes pesky and occasionally neglectful; information is frequently sketchy; and the quality of the cooking, or at least the backup, varies from night to night. If the bistro is to become a regular destination, it needs a little more character and a little less personality.

If you believe that "escargots" is French for "sponge," and that the snails are only there to hold up the garlic, you'll love these; so potent are they that they were olfactorily obvious before the kitchen door finished opening (and that was from across the room). The house pate is very good, but it was served so cold its flavor was bound up tight, and the entire plate -- terrine, tomatoes and lettuce -- was without even a drizzle of dressing or condiment. The fact that the empty bread plate sat there helplessly, so that the pate had nothing to snuggle up to and get warm, was even more puzzling. And in the last few months, I've noticed a widespread truculence among chefs when asked to cook duck breast or lamb rare, and Bistro des Celestins fell right into line. The kitchen didn't argue the order, but sent it out so showily rare that it was all but raw and, more seriously, unseasoned and unsauced.

But Celestins does many things very well. (Even that lamb steak was almost rescued by the fries.) Minute steak is one of those deceptively simple dishes that French bistros just seem to get exactly right. The merguez-style Toulouse sausages with lentils were tasty, although again the plate seemed a little bald. ("Presentation" is not a word one associates with this place.) One night's special lamb shank was a little chewy and clumsy to eat, but the meat was delicious -- and I'm not proud; I gnaw bones. Potage Parisian, a sort of lighter vichyssoise, is extremely soothing. Clam chowder was not overly stewy-chewy but discreet and with nicely flavored broth. Fried calamari is greaseless, and the remoulade good. The pork chop was perfectly pleasant, and the mashed potatoes even better, ungussied and ungarlicked; but a request to have the chop cooked rare rather than medium was denied because health officials supposedly forbid it -- the first time I've heard that. The cold artichoke appetizer was a little undercooked on at least one occasion, but frankly, considering how many places in town bring out overcooked, soggy ones, it was relatively welcome.

There are several fish dishes -- the delicate frog's legs, as is traditional, being listed as seafood -- and they're all pretty good bets: tilapia, salmon, swordfish and commendable mussels with those fine fries.

The wine list is fairly brief and moderately interesting (perhaps a little overpriced for such a casual menu), but the staff has a habit of standing over you and "suggesting" a wine rather too strongly before you even have a chance to consider the options. Not that the recommendation was so bad, but it made it sound as if the restaurant had a few extra cases getting old in the backroom.

The bread is very nice (like many restaurants, Bistro des Celestins buys fresh dough and then pops it into the oven as needed), but I say again, white linen tablecloths and foil-wrapped butter should be mutually exclusive. I'm also one who believes that plastic flowers are worse than none at all (and certainly no comfort at the end of a hard commute). This is the sort of place you really want to like, and to see do well; let's hope it learns to show a little more love to its patrons.

French bistro-style dishes, such as the traditional frog's legs, are nice choices at the Bistro des Celestins in Arlington.