There's nothing wrong with the glass dividers IMO. They keep some of the draft out when waiting at stations, which due to the padded timetable, will inevitably occur. Whilst there is something to be said for having a standard fleet of four coach twenty metre units, it's worth pointing out that a 12 350/1 seats nearly fifty fewer standard class passengers (549 vs 598) than a 10 444, although it does seat two extra first class passengers. As for bike spaces - at least they are provided, and in a fairly decent number. Most modern stock has little or no bike provision.
Although to be even fairer, the slammers were more comfortable than any post 1998 stock. Not just EMUs, but trains as a whole. Plus you knew you would get to your destination.
You might get to your destination, but you'll either be sweltering hot or freezing cold, your breakfast and any hot drinks will have evacuated themselves to the seat opposite, and if you're on a VEP you'll have people clambering over you at every station trying to get out. As Ainsworth points out, 444s are hardly unreliable - in fact they're the most reliable fleet of EMUs operating in the UK.