What I like about the site (as an engineer and someone who's worked countless hours on graphical user interfaces) are:
1. The font, colour scheme, and layout: Very well chosen colour scheme and font, one that doesn't put any strain on the eye, has good contrast, and the navigation from one link to another is very easy (logical, if I may let a little bit of the engineer side of me comment).
2. Quick search: Be it in real life, or on the net, people hate waiting. The search functionality is easily one of the fastest I've come across, and given the sheer volumes (OK, numbers) of restaurants in their database, it's mighty impressive.
3. Pictures: Pictures speak a 1000 words...then what would 1000+ pictures speak? Right from the git-go, Zomato has made it a point to focus on pictures - collected from all possible sources (which made them stand apart from their competitors). And how can one not have pictures when it comes to food? :) the more the merrier.
Some of the things that that didn't quite catch my fancy, that I'd maybe like to see changed are:
1. Replacing original copyright marks on images: While Zomato has done the right thing in putting their watermark on the images, I think it would've been a nice(r) gesture had they retained the original copyright mark of the person who submitted the image simply so that it becomes an almost symbiotic relationship with the original image provider. While I'm not too sure about legal implications (Zomato does explicitly state that the images used aren't all their images and take explicit permission to use the images), having both the original copyright, as well as the Zomato watermark could be something that would've been greeted with slightly more cheery faces.
2. Open now: While the 'Open Now' feature was indeed a novel introductory feature on the site, it's been on beta for far too long (for my liking). I actually think this is something that would be quite beneficial for those who eat at odd hours (I'm sure this group is quite a large number), and also another one of the differentiating factors between Zomato and its competitors.
3. Recommendations by Zomato/editors/experts: The editors/experts, who've been chosen by Zomato for writing reviews to help boost the credibility of the reviews & ratings for a restaurant, should also be provided with a section to give their recommendations for restaurants in almost every cuisine. This way, if a user who visits the site with the sole intention of finding places that serve, let's say burgers, then he/she can search for that and among the search results, the first few should clearly indicate that these are the places Zomato recommends. The remaining results can be displayed in the existing order.
As far as UI suggestions go, I have a suggestion for getting alerts from Zomato about various 'events', both under the Restaurant Guide as well as the Events section. It would be great if a dashboard of sorts is set up for user who log into the site with their logins. Upon doing so, they will be presented with a divided screen, the left side containing a notice board or a dash board of sorts, where a one-time activity of customising the alerts can be done.
Clicking the 'Click here' link should take the user to a tab on the dashboard where he/she can select the alerts based on the list provided. The list would have to be provided by Zomato based on what they think would interest the users most. The user then proceeds to 'check' the options of where and how to receive the updates. Also, an option of allowing the user to select specific restaurants that he/she may love and would be interested in knowing about any new event/dish/update about could be provided in separate tab.
The text box can be AJAX-based and as the user starts typing out a name, options can appear below and the user can then select a restaurant name from the options displayed. The selected options can be then shown in a table below, where the user can again select where and how they wish to receive the alerts about these place.
After selecting how he/she wants to receive the alerts, the save button can be clicked so that the settings are saved.
Once the settings are saved, the next time the user logs into the site, he/she can get a snapshot of the alerts on the dashboard (if they had chosen the dashboard option), and by clicking the appropriate option, can be directly taken to the page with the details rather than scouring through the site (events section) in search for the specific event. While this may not be a revenue generator, it could certainly boost the users usability experience on the site.