I have an electronics design and manufacturing business and have been doing this since 1978.
Lead-free soldering works OK for the normal sort of large-ish components used in most industrial products, although for fine pitch devices it remains unproven in the long term, and some firms using very small parts (Swatch was a high profile example) have found reliability poor.
The main reliability issue which remains is the higher soldering temperatures with lead-free solders. These push some items like surface mount electrolytics close to their absolute maximum temperatures and just a few degrees more will damage the parts, but not in a manner which is obvious...
The whole ROHS initiative has caused huge problems for manufacturers because many old and proven components (older embedded processors in particular) never became available in lead-free versions, and consequently many products had to be scrapped. Estimates of how many products were scrapped due to this are obviously hard to find but some suggest it is around 50%. I think that is about right, and results in a massive wastage of design resources (products having to be redesigned), electronics hardware ending up in the landfill, and non-ROHS component stocks ending up in the landfill too.
ROHS is misguided since the vast majority of lead entering the environment is from discarded car batteries and these cannot be banned, and also because the concept of lead escaping from a modern dry landfill has not been established. So this is a hugely expensive
precautionary measure.
There are fortunately exemptions to ROHS. The military, internet switching equipment (evidently Cisco had a very good lobbyist in Brussels
), medical, and "control and monitoring" products (the exemption many European companies including mine are making heavy use of). I don't know, without looking it up, whether avionics is exempt but it probably is - most of the designs on the market are 10+ years old.
Distributors of electronic components love ROHS because it forced a huge increase in demand for new components, which command higher prices compared with old ones, and because companies had to scrap a lot of inventory. The distribution industry is constantly lobbying the EU to terminate the existing exemptions, unsuprisingly. Of course, if you have a job as an "ROHS compliance officer" in some company then you will also have a predictable view
The electronics industry publications are funded mostly by advertising from electronic component manufacturers so they also favour forced obsolescence.
The next gravy train is REACH....