Allen materials are (or were) extremely outdated. For instance, Allen asks stuff about what will change in GIPS in 2005 - that’s not really that bad until you realize that any questions about current GIPs are actually about GIPS around 2002 or whenever they wrote them.
The same happens for almost every section. It’s probably better than absolute nothingness, since a lot of the curriculum from 10 years ago is still valid to some extent (to CFA or financial knowlege in general), but I would rather read whatever is on wikipedia than take Allen’s questions, especially close to an exam.
A lot of Allen’s questions are also practically identical to QBank. For L3 it was something like having a different vignette, but basically the same question and the same answer choices. So I guess it’s a little like having 2002s QBank on your phone.
Throughout my CFA preparation I came accross some of the materials from CFAI, Schweser, Stalla, Elan, Finquiz and BSAS - in my opinion Allen is easily the worst of them all.
For L1, Elan had a product they called “2000 questions” (this was late 2010) - I thought the questions were pretty good overall. EOCs and blue boxes are always nice - probably much better to go through them a second or third time than to use Allen.