I’ve been using Airtel 4gLTE when I work from home. It has worked fairly well in the past. Though the speeds were never even close to what was promoted in the ads, it did suffice the purpose. It also provided a good wireless alternative to the BSNL broadband which I have at home, which is highly unreliable though much faster when it works.
Lately however(since Jul, Aug 2014), the Airtel 4G speeds have dropped considerably. A test on www dot speed test dot net shows .12 Mbps download and .11 Mbps upload speeds(which in lay terms can be read as pathetic).An adverse post on Airtel FB page did invoke them to message me immediately. I provided them my contact number but am yet to hear back 24 hrs later.
I would recommend that you first check the speeds in your area with a borrowed device before you purchase this product. The only reason I would recommend this product is because it is the only 4G offering in Bangalore and it provides a good alternative for those who cannot take fixed line broadband connections. All other providers only offer 3G devices which have the same problems as well.