I can relate. A dirty, noisy, hot Pacer/150/156 over an air-conditioned, spacious and clean train that Joe public want to travel on? Truly bizarre. Really does boggle the mind the people on here sometimes....
Dirty v clean? I can't imagine why a 195 would generally be cleaner than a 150/156. Trains either get cleaned or they don't, and how well they get cleaned, when they do, often depends where they have spent the previous night. The 195s used on the Manchester Airport to Liverpool Lime Street service (which is the one I presume you use) are, for the most part, stabled overnight at Allerton or Newton Heath - so, no excuse for them not to be clean. One unit does actually do two days (Friday/Saturday) without visiting a depot in between, it would be interesting to see how that one fares.
Noisy? Yes, a 150 and 156 are both noisier than a 195, but Manchester Airport to Liverpool Lime Street is an interurban service with not many stops, noise shouldn't be so intrusive.
Hot? Depends upon the time of year - most of the year it shouldn't be a problem, I'm sure.
Spacious? Not a 195, if it's replacing a double 150 or 156.
I travel on the 195 everyday from Mauldeth Road to Piccadilly. Teething problems aside - they are 10x the trains than the 150s and 156s they replaced. That is the opinion shared by a couple of my relatives and friends who also use services operated by the 195.
Mauldeth Road to Piccadilly is hardly a fair test, it's on the least patronised section of the route. A fairer test would be into or out of Manchester (to/from the West) or Liverpool, at peak.
It's already been decided where the bulk of the 195s will operate has it not? Most of the Northern Connect routes + potential cover/odd diagram elsewhere.
Indeed, but I'm still saying that those aren't necessarily the ones the 195s would be most suited to.