Having grown up in North Wales and been subject to First North Western, Wales & Borders and Central Trains, I have to say that if Arriva Trains Wales offered anything during its time, it was greater stability and clearer organisation. I've lived in North Wales, South Wales and I live in Merseyside now, but each region has its own shortcomings.
I, more than anyone, understand the problems with ATW. Try catching a North Wales Coast service to Chester when Chester Races is on, and you'll see what people mean ("sardine can" is an understatement). Reliability on the NW coast was often an issue when I lived in Colwyn Bay and many people were always quick to blame ATW for "not putting enough carriages on". Delays of 30-40 minutes are regular on the Wrexham-Bidston line and minor delays are almost always expected. Stations such as Shotton and Llandudno Junction offer poorly timed connections. When I lived down South, the issue lay with the popularity of the commuter Valley Lines services at peak times and the unreliability of the rolling stock. The Cardiff-Swansea-Carmarthen-West Wales services were simply a no-go in rush hour. Sunday services are generally below expectations throughout the franchise area.
But beneath all of this, I fully comprehend that ATW has been dealt a bad hand in the first place. Of course the franchise spec is let on a no-growth premise, which is a nonstarter in the first place if the franchisee was ever to make any improvements. I generally think that ATW get that the franchise is flawed and that the lack of rolling stock is a huge barrier to any investment they wish to put in it. I generally see the W&B franchise as an improvement over FNW, CT and NX W&B. Coming from my perspective in Wrexham, the service Wrexham General receives today to a wider variety of long-distance termini is a world away from where we were in 2003. People can argue all day long about the appropriacy of the Cardiff-Holyhead and Birmingham-Holyhead bi-hourly services, but the reality is that these routes have enabled more joined-up thinking and economised what was already running into a single route anyway.
As for the rolling stock - we know the WAG paid for most of the refurbs on the 158s and 175s. ATW's 158s were some of the worst on the network before they were done. Also remember that right at the beginning of this franchise, ATW had to sublease a number of its 175s back to First North Western for TPE services, relying much more heavily on 150s, 153s and 158s for medium distance services. Hell, it was only just before the commencement of the ATW franchise that some FNW routes such as Wrexham-Bidston were run by 101s! The 175s were unreliable, there were stock shortages on the Valley lines and little consistency accross the network. The ATW franchise period has seen things become a lot more stable, consistent and joined-up.
I think the vast majority of ATW's staff work incredibly hard, and as I am now out of the ATW region, coming back onto an ATW train always feels homely and secure. ATW has predominately taken the franchise spec to the letter and this is a huge shortcoming for it and its reputation, but at the end of the day that is the fault of the political agreements that were made at the time. They could (and maybe some would argue, should) have spent more, but I'm sure given the mess of a franchise the SRA/WAG let on, any private company other than Arriva would have done as little as possible to sustain the contract they had signed. Out of the 'no growth' franchises, I would say that ATW has certainly come out as more unified and professional, rather than the off-cuts of three other franchises.