I have several Strontium micro SDHC cards and I have been using them for over 4 years.
I have not yet faced any problem with them.
Also, they are Class 6 SD cards and hence give a very high data transfer speed.
The best part is that they are comparatively cheaper than micro-SDHC cards of other companies.
So, it is really great to have high speed microSD cards at such cheap prices.
Also, Strontium gives lifetime warranty for the microSD cards which is a plus point.