I travelled on a 730/2 recently for the first time (730214 to be accurate), between Stafford and Crewe (was a Birmingham - Liverpool service).
My first impression was just how big and spacious the train felt, including big windows, lots of seats, and bright lighting. I liked the train information display on how/what level each carriage was in terms of capacity. Definitely feels like a new era train. The other thing that struck me was just how quick off the mark it was when leaving Stafford, very fast acceleration which felt great.
In terms of comfort though, I travelled in the normal standard class area/seats. The seats felt very thin and hard but tolerable for the journey I was taking, not sure how I would feel on a longer journey. They are much better then the 730/0s which are too small for someone my size.
The 350(/1, /3 and /4) seats are still to me far more comfortable to travel on longer journeys.
The fold down tables feel / are too small, I think I would prefer the 350 ones too, but at least the new ones are mobile phone / tablet friendly with the grooves.
I noticed the train was rattling and vibrating quite a lot which made the journey not too great, the 350 I travelled on in comparison on a previous journey was very smooth and hardly rattled at all and was unnoticeable , so for me the 350 wins here too.
I didn't get a chance to travel in the declassified first class bit so will need to give it another go and try this part next time.
Overall and as of now, I still prefer the 350s, but in comparison to the 350/2s, I think the 730/2s are a welcome addition and will certainly do a really good job with carrying lots more passengers on the routes it's destined for, especially London Euston - Crewe.