Tag Junior (now rebranded as Leapreader Junior) has been very popular in our house, to the point that my son is having his second Tag Junior this Christmas.
The major downside and the reason my son will be having a second is they only take approximately five books at once even though some of the sets come with more than that. They are a pain to swap over as Leapfrog Connect keeps crashing (and in my case my son wouldn't let me anyway, he is autistic and wouldn't understand why the books sometimes wouldn't work). Also some items take up more space than others, so you might be able to fit five smaller books but only three if you wanted the flashcards as well because they take up more space than one book.
It is a great toy, my son has got loads out of use out of them, he likes to take them to bed and goes through the books clicking on all the different parts of the pictures. He doesn't have an interest in the story, he just likes the different sound effects on the pictures.
It is a well made toy aside from the storage issue but how much fun a child has depends on which books you get. Some of the books are better than others, sometimes they seem to think because they have got a character on people will buy them anyway and that is all the effort they need to make.
Of the ones we have:
Good ones with lots to do: Curious George Colour Fun, Thomas & Friends, Winnie the Pooh, ABC flashcards
Just ok: ABC animal orchestra (a Christmas one but I can already see it will be so annoying), Sesame Street Monster Faces (good but doesn't do a lot so he gets bored with it quickly)
Bad: Dora 123 (barely anything to do, apparently sticking the Dora character one was the most effort needed), Team Umizoomi (has the Amercian voices rather than the ones used on the cartoon played here)
If I could get more I would get the Cars ones as I got a sample and they seem to have a lot of do and the other Winnie the Pooh as it seems to have a lot to click on.
For us they have been a big success toy and if he is ready developmentally we plan to get the Leap Reader Junior next Christmas.