Having lived in a couple of light rail served cities (Manchester, Nottingham), as well as regularly visiting others (Sheffield, Newcastle), I've definitely got a fairly good taste for light rail in the UK!
In terms of Nottingham Express Transit, I have to say that while the infrastructure/rolling stock is pretty standard, where it excels is service. Frequency is great, ticketing is straightforward and things like wayfinding, branding and design are modern and simple.
Systems such as the Supertram and Tyne and Wear Metro feel rather outdated in comparison. Metro doesn't exactly run a turn up and go service, while the Supertram has the odd onboard payment and paper tickets.
Metrolink is odd, but honestly feels pretty modern and easy to navigate. The main issue is the interlining to the extreme between Cornbrook and St Peter's Square. I'd say the biggest issue is the system is a little confused - in many ways it is close to being a metro with pretty long, high floor trains. However, it just happens to run on the street through the city centre, with some pretty questionably safe infrastructure around Piccadilly Gardens...
Growth has been a bit slow for many of these systems, however Metro seems to slowly be marching towards modernisation - the new fleet coming this year should help, along with the start of work to renew track, power systems and signalling, which should hopefully mean more frequent service!
Supertram obviously has the tram train project, but I really think they need to make a better effort to modernise the system and run more frequent service on some routes!
Nottingham Express Transit needs to seriously work on getting trams better segregated from traffic through Hyson Green! There are also a number of areas that remain unserved and some missed opportunities for connections. Personally, I would like to see an extension of the Phoenix Park branch out to Langley Mill (to connect with heavy rail) although even Giltbrook would be a good start! Extending Toton Lane branch to Toton Sidings is an obvious move too, HS2 or not!
One of the key differences between much of continental Europe and UK/Ireland is the distribution of population. Mass transit systems ie trams/light rail are most cost effective (ie operate with less subsidy) transporting people around higher density conurbations where families typically live in apartments, rather than sprawling estates of two-storey houses with small gardens. It isn't completely black and white, but if we want more continental-style light rail we may need we adopt more continental-style approaches to how and where we live.
There is a definite issue with the over-use of light rail in many circumstances it isn't designed for. However, I don't think trams should be resigned to on street running through city centres/dense neighborhoods.
I just think people should be prescient of the limitations of light rail technology and should evaluate each project on it's merits. For example in the states, there is definitely an issue with running trams to far flung low density suburbs, with pretty pitiful average speeds. (This is where metro/regional rail would arguably provide a better alternative.)
Countries like Germany I think offer a good vision of this balance, with smaller cities running tram trains in the place of a heavier metro system, with bigger cities having S-Bahn/U-bahn systems. It is also very dependent on geography, layout and demographics.
Yes housing density is certainly a factor, and no doubt bus deregulation has been another. On the continent buses act as feeders to tramways, with integrated ticketing, rather than trying to compete. No doubt bus companies have been whispering in the ear of the Treasury, saying how they can achieve the same result as light rail much more cheaply, even though achieving modal shift with buses is much more difficult.
Totally agree, following on from above, plans for new transport should come hand in hand with plans for redevelopment and creation of new neighbourhoods, for example on former industrial land. Developing transit-first neighborhoods helps to reduce concerns about increased traffic, as well as reducing the amount of parking developers need to provide new residents (saving money/space).