"How's it going?"
"What have you learned so far?"
"How much better/faster/stronger/larger is it going to be?"
It's an attempt to start setting expectations early, and that's fine. It's even all right to answer the question, to describe what you know so far, and to provide interim results.
A warning for all of the askers out there. You managers, you customers, you project managers, you team mates.
Interim answers may prove to be wrong.
Halfway through a project, the team may have an inkling of the benefits, but a lot can still go wrong (or right!), and the end results may be very different. For example, we might have some great performance improvements.... but not yet have discovered the fatal flaw that negates them. Or we might have something that now lets us handle 100 concurrent users.... but not yet have done the test that shows we can handle 1000. We say, "we think X", but we might be wrong. We'll know with more information.
So please, feel free to ask the question. Just be prepared to later hear a different answer than the first one you got. Don't make the interim results public, and don't make decisions that require the results to be precise; they may change a bit and you need to be aware of that. Instead, take them for what they are: current status and partial understanding.
Ask questions to understand risk. Ask questions to get a sense of progress. Ask questions to let people share things they're excited about. All these are great reasons to ask for interim results. Just be prepared for the time when the word interim is important, and the final results don't match - for better or for worse.