The Committee on Standards in Public Life claims that the signature level is too low for the recall, though their claim that it is lower than in other countries is (at least in regards to the US) incorrect.
Most states have a requirement tying the signature requirement to voter turnout, which is far lower than the amount of voters in the district. Note the Chattanooga example for how the total voter v. voter turnout standard can be played out in real life.
There is committee also complains about the use of post or proxy signatures -- meaning that they would not be gathered by petitioners, but send in by voters. We've had that discussion in the US. It certainly would make the recall easier to get on the ballot, but it also might limit instances of fraud. The question is how hard to they want to make the recall -- and who should bear the burden.