What are your expectations for a GPS?

I think it's fair to assume that the performance of this module will be much the same as any other 'L1' module, It does have GPS + WAAS / EGNOS and Glonass, there is a data sheet for the NEO-7M here :-
https://www.u-blox.com/sites/default/files/products/documents/NEO-7_DataSheet_%28UBX-13003830%29.pdf
Extract from page 6:-

 

Expectations have definitely improved over the years, the first GPS I owned some 20 years ago definitely did not work in doors at all, by adding another set of satellites, EGNOS / WAAS, parallel satellite tracking and much more sensitive receivers, this has changed somewhat, however although it is sometimes possible to maintain multiple satellites when sitting in-doors and 12 feet from a window, it is still very difficult to get an initial 'fix' when in-doors and you should not expect this. GPS's still require direct 'line-of-sight' of multiple satellites to guarantee an 'initial fix' and your customers should not be expecting anything from in-door use. Devices that say they can navigate in-doors usually rely on a 'last known GPS' position and then use dead reckoning in the device (accelerometers, movement sensors etc.).

I would say that your findings are normal and what you should expect, i.e. you won't get be able to improve the performance without using a very much more expensive and bulky unit