Well, I've done my trip to Hel and back, and it was definitely worth it.
Got there directly from Gdansk on an old non air conditioned rake of double decker coaches hauled by a diesel shunter-ish sort of thing. This had come from somewhere beyond Gdansk and it looks as if it comes in in the morning, then does some of the Hel<>Gydnia turns, then goes back to where it came from in the afternoon. The rest of the local trains I saw were a single coach sandwiched between two low floor DMUs, apart from one I saw at the end of the day that was a single unit hauling a coach.
The train before the one I got back was absolutely crammed - people wedged into the doorways. But the one half an hour later was much more civilised - only a few people standing and it really emptied out.
It would have been pleasant enough just riding in the old coach with large opening windows, but being able to look through both ends of the coach and see the sloping front of a DMU was a rather unusual experience.
It was cloudy for much of the day, and not a weekend, but still busy. On the other hand there was some kind of D day celebration going on which might have attracted more people (lots of old WW-2 era vehicles driving up and down with people in uniform or appropriate civilian dress).
From looking at the traffic on the road parallelling the line (the road to Hel) I would have preferred to be on the train. (Well, I would anyway).
Hal was rather crowded but it seemed very much geared up for domestic tourism, unlike Gdansk. Ordering lunch in a cafe was quite entertaining - the waitress was very friendly but just kept talking Polish even though it wasn't getting through.
The rest of the trains in that area were pretty good too - some unmodernised EMUs with big opening windows, and lots of loco hauled Intercity trains which included one formed from an Intercity liveried diesel shunter-like loco hauling just two coaches. (I assumed that when the app showed just two coaches it was malfunctioning, but no).
Getting the ferry back would have made a nice round trip, but the times didn't work out and anyway the trains were too interesting to not want to go back on one.
I'd highly recommend the Gdansk area for both the rail interest and more general tourist sights.
(A trip to Elbląg is well worth it too to take the boat trip down the Elbląg Canal where the boat travels over five funiculars - unlike most boat lifts the boats sit in a cradle rather than a caisson full of water. Interesting trams in Elbląg too)