The cover fits perfectly on my Galaxy S4 and nothing wobbles. The only criticism would be the signal degradation (approximately 10% in mobile use and 12-15% in the tub - the area), but this is so mainly on the positioning and strength of the antennas.
In addition, the company has a very courteous service, the help was reaching me with an inquiry to the side
Conclusion: If you want to take the somewhat poorer reception in purchase, it is worth buying!