I can see no one has fully explained what the pitfalls are. There are multiple issues including doubling ground rent clauses, reversion to assured shorthold tenancy, lease extension problems, cladding issues post-Grenfell.
I suggest you buy yourself a copy of Louie Burns book. I also recommend joining the National Leasehold Campaign Facebook Group. They've been instrumental in pushing for leasehold reform. If you have questions, they are the group to direct those questions towards as there are some very knowledgeable people on there.
The reason you're finding it hard to find reliable information on this is because leasehold legislation is complex and poorly understand by the general public, mortgage lenders and conveyancers.
There are many reasonable leasehold properties out there with very long leases and peppercorn ground rents. You should swat up on leasehold before making any purchase so you know how to distinguish between these and the more problematic leasehold properties ("Fleecehold") I'm talking about.