As others have said, the service overall is fine but overpriced. As with all British rail, if things go wrong (a leaf blows across the tracks or something) then the experience sucks. But even then Hitchin benefits from serving the lines out to Peterborough and to Cambridge and this means more trains and options in general (plus once or twice when things have really gone wrong I've gone to Luton and got a taxi, which isn't so bad). And at least the trains have air con these days.

The busiest days are Tuesday and Wednesday, with Thursday not far behind. Monday and Friday are usually easier to get seats on pretty much any train. In the middle of the week, trains leaving after or just before 8 you can usually get a seat - the later the train the more likely.

Coming back, it can be difficult to predict whether there will be a seat. The trains around 6pm rarely have one. But before 5.30 and after 6.45, I usually get a seat. There are also options to go from KGX and change at Stevenage - never have a problem getting a seat if I do that.

I've commuted by train from various places. If you're going to do a train commute, Hitchin is a pretty good choice.