the most remarkable feature is it's support for IOS 5.1, which would add a big value point to such so called outdated tablets, if it (really) performs as demonstrated.
I'd go with the cable based version unless it's for (say) server administration and such tasks.
The price is low midrange in my estimation (less than 10 cheap, 10-30 mid, above 'high').
But considering price versus delivered results most quality apps are in fact cheap.
One of my favorites is the virtual Fairlight CMI (from Peter Vogel, one of original hardware developers). $50 get you the full user experience of the original using a stylus (the most simpel does) plus the original libraries. They even fake the disk operation and noise.
I really like the crude sequencer as a composition tool - it leads to very particular lines just by it's mode of operation - and it's a piece of history.
Another rare classic is iVCS3, an EMS Synthi emulation by Apesoft.
Apesoft and Amazing Noises are synonyms for the same developer team.
Their ApeFilter, Sparkle and Moebius sound processors are indeed... amazing.
There's a Mellotron app for $50-70 with all 'tapes' included - reads high, but the exact same content is about at least $300 from GForce on PC.
Palm's PPG apps are in the $20-30 range and have an outstanding sound quality.
Complex stuff by nature, but that's WT synthesis.
Last but not least an ad hoc sampler/resampler with extensive sound mangling: SamplR.
A true classic since the early days of IOS.
Just this single app for 10 bucks is worth an iPad One and an ioDock One alone.
One of the best regarding simplicity and workflow that I know.
ps: I may add that I don't mind geeky gimmicks - it's all about usability and sound for me... and I'm very(!) picky about the latter. I still have a Creamware DSP system and PT TDM.