I looked at the peak trains on Monday, and a single train (the 17:36 off Swindon) yesterday / Friday. Loading at Melksham for the 17:36 is over 50%, with the majority of passengers carrying on through to Trowbridge, but a good number getting off at Melksham too. The temporary extension to car parking at Melksham is certainly already required and in use, even though a high proportion are walking ... and truly in use for rail purposes rather than convenient parking for nearby businesses too
The 19:17 (18:50 off Swindon) had dropped a bit on Monday from what it was (at 19:11) prior to 9th Decemeber, when it was the only southbound train of the day after the 06:38. Not a huge drop, and the numbers were distorted on Monday by the departure of the train from Swindon prior to the arrival of the official connection from London ... newcomers waited for the 20:12 off Swindon, and weren't best pleased.
General reaction is very positive; there does seem a view that even if buses are 45 minutes late / cancelled because of flooding, trees down, etc that trains should still be able to run on time. And a view that a train every 2 hours doesn't provide the flexibility everyone needs - actually, I've a lot of sympathy with that latter view and I'm coming to realise that (in theory - don't expect it in practise
(yet)) that a second 153 buzzing up and down, passing the first one we've just got at Chippenham every hour, would probably load well and indeed would make so many more journeys possible that it would load the first train more too.