I find it difficult to find sandwiches in Hong Kong and even more difficult to find good sandwiches. Grove is surprisingly good for what it is.
First, how to get there: it's right at exit D in the Hong Kong station, down at the level where the trains are, right around the corner from the Disneyland booth.
Second, what you can expect to find: there are a number of pre-made sandwiches, pre-packaged on a shelf. There are a number of 'salad' sandwiches-- tuna salad, egg salad, shrimp salad-- I don't go in for that stuff myself. On the other hand there's cheese, ham & cheese, smoked duck breast, and chicken caesar. In addition, behind the counter there are several pre-made panini sandwiches. These look like sub sandwiches, but if you order one they stick it on the panini press for a few minutes and it flattens into, well, a panini. The paninis have the same names as the regular sandwiches (e.g. 'smoked duck breast') but they actually contain more vegetables.
On separate occasions I have had both the chicken caesar sandwich and the chicken caesar panini.
Chicken caesar sandwich: This, like all the sandwiches it seems, comes on two slices of whole grain or multi-grain bread, rather than the gross white bread you get on sandwiches from the circle K. I found the bread to be particularly tasty, more so than bread normally is. So thumbs up for that. The other ingredients are fairly straightforward: chicken, romaine, parmesan, and caesar dressing. They don't overdo it on the dressing, which is commendable, and the chicken is tasty, if a little overcooked. It could use more veggies though, it felt a little insubstantial. Overall 7/10.
Chicken caesar panini: Here you get the chicken, romaine, parmesan, and caesar dressing of the regular sandwich, but you also get cucumbers and tomatoes. The sandwich is warm and gooey from the panini press and the bread is nice and crunchy (though not dry). While the bread is very different, I think their panini bread is even better than their regular sandwich bread, which as I said is pretty good itself. Overall 8/10.
I'm disappointed that the selection here is so limited for the classic meat + cheese sandwiches: there's no prosciutto and mozzarella, or roast beef and cheddar, or turkey and provolone, or pastrami and swiss. (By the way, if you want any of those sandwiches, except the turkey one, you can find them at the city'super, which is only a short walk from Grove.)
Final score: 7/10
By the way, this location is only open for lunch and they're pretty busy between 1 and 2. If you come after 2 or before 1 though, there's no wait at all.