Updated software is nothing better than the old one. In fact following are some first level observations compared to the older flat UI:
1. Slower EPG
2. No number navigation in Guide
3. Slower startup
4. Un-necessary glossy interface, doing no good to users, but increasing navigation delays a bit. The UI does not feel snappy enough and any one used to Tata Sky's old and fast interface will need some time to adjust to the slowness.
6. The up and down key now switches programmes in the banner bar, and left right will switch channels. Again something which needs adjustment.
7. Favorites in TataSky were never properly implemented, and now it is same as Airtel, worse. Airtel actually had an excellent implementation earlier but it screwed the same with a similar update last year.
NOTE: This firmware builds on the same version which Airtel circulated last year. The same problems are seen - slow startup, slow EPG, bad favorites, etc. Airtel and Tata Sky have the same middleware provider, hence similar UI issues.
However, the channel change (i.e. time from when you select a program in the EPG and the time it takes for the picture to appear) is more or less same as earlier. May be with MPEG2 its fast, need to see how is this affected in case of MPEG4 channels in the future.
VERDICT: Consider yourself lucky to be on old software (Thomson grey box). The new software is only for the glitz lover and does not any value beyond glitz.