There have been many discussions about Keens on this board, a quick search turned up these threads you can read through.
As for myself......it's certainly a good place, old boy's club type steakhouse. They are really known for their mutton or lamb but the steaks are excellent. Personally having been there a couple of times in my life, I have no desire to go back, I enjoy some of the newer places.......but if you have never been it is certainly worth a visit, then you can take it for yourself from there.
I eta there once a week for lunch - perfectly reliable, great food, solid service, don't know about the wine list because I don't drink at lunch but impressive bottles seem to be on those tables who do imbibe....really cant go wrong - the mutton chop is HUMUNGOUS
There are indeed tons of reviews on this site, but I can jump in now to let you know that my experience this past Friday really exceeded my already high expectations. A group of three of us split the mutton chop (really, truly one of the best cuts of meat I've ever had), the porterhouse, tableside caesar salad, and the mushrooms/creamed spinach/and hash browns for sides. Unanimously, we loved each dish, which is to say nothing of the old world, classic ambiance.
I 100% recommend this place.
Large pieces of excellent lamb and beef, cooked the way you like them
And a list of Scotches that is amazing (I am not a Scotch drinker, but it is some list).
What's not to like?