We took ds out of Acorns House Acorns (same chain, Park Place, near uni & museam). That was last August, after a series of events.
What swayed it in the end was that staff-child ratios were NOT being kept, (1 staff member to 14 babies on the final, trigger, occasion) and he was allowed to play on age-inappropriate equipment without proper supervision. Also,I saw a member of staff shouting at a child not once but twice-raised it the first time but took him out after the second time.
Most seriously, my parents (not known to nursery staff) were able to go into the nursery and take my son without giving the password or really being asked who they were.
The management took our concerns very seriously, had a 1 hour conversation with them-unfortunatley we then went downstairs afterward to find 8 children with 1 staff member.
Jigsaws are pricey but good, I think they employ 100% qualified staff (heard somewhere 100% NNEBs?), which is why they are so pricey. On the Cardiff Mummy circuit, its one of the few that I have heard nothing bad about.
The following have bad reputations on the Cardiff Mummy circuit (possibly unfairly): Ninian Park (closed and reopened x 3), Toybox, Nazareth House, Tylsiau Bach/Little Gems, Heathfields.
Little People & Asquith Court (at David Lloyd) are both reccomended also.
I thoroughly reccomend Liliput, in Gabalfa, but they have very limited places unless you work for local government or civil service.
I do only know about Roath/Penylan/Splott type area though, so can't help too much.