Tommy K's is a superior video store. Sure, most people will swear by Best Video in Hamden - and they might have a point if you aren't a fan of mainstream media at all. However, Tommy K's consistently has a good selection of large and small movies, and, more importantly, hires great youngsters to work in their stores.
Tommy K's of New Haven isn't a disappointment in this regard - the kids are knowledgeable if you have a question, quick with a recommendation, and chat with you when you ring up your rental.
That said, the store layout is awkward, and the selection isn't quite as good as in other locations...and it's a little unnerving to have an everpresent security guard in the evening hours.
Still, if you're in the Westville area, it's a step above Hollywood Video or (ptooey!) Blockbuster.
Note: Like all Tommy K's, on long weekends (about once a month), used DVD's sell for cheap - usually 3 for $20. It's a nice deal.