Lol, man - so many "experts", but only a few people actually tried it.
Maybe the drop to $2 soothes your prejudices?
The front page review nailed it, especially the part about IAP (premium currency for additional dlc/content).
All things considered, the IAP in the game isn't all that bad. There's a in-game shop where you can purchase items by way of the core currency you earn by completing stages, and the other currency -- "R Tokens." These are a premium only coin that allows you to purchase certain items and extra levels, which can be basically considered DLC.
The good news is the vast majority (if not all) of the shop's offerings are optional, and have no real bearing on the game. There's also a ton of "extra" missions that cycle in periodically for free, so you won't be at a loss for things to do when you consider the fully featured campaign.
The game got 4,5/5 stars on touchArcade and 4 stars on 148Apps.