We've taken the metro into Lille on three of our four visits, we stayed in nearby Roubaix and took the Metro to the center of Lille, the second time we drove to Roubaix, parked and took the Metro, the 3rd time we stayed close to the St. Philibert metro station and drove from our hotel and parked. It's very quick, service is frequent and a round trip ticket is 3€ (September 2013), there was also an all day pass for 4€ or a Grand Braderie Pass for 5€ which I assume was good for the whole weekend. You can get off at the Gare Lille Flandres stop and you will be right in the heart of the market or we also got off at Lille Grand Palais and then returned from the Gare Lille Flandres stop.
From St. Philibert, the ride was about 20 minutes, there was plenty of free parking when we arrived, when got back the lot was pretty full but it looked like you could park across the street in an overfill lot.
To locate the Metro station, look for the M sign in the attached photo
Only the metro is worth a visit to Lille. This new generation of metro systems, a kind of small profile light railway, is so spectacular because it operates automatically (the so-called VAL system which stands short for Véhicule automatique léger).
The metro vehicles are very funy because they are so small: only 2 m wide and 26 m long (two linked cars). They run on rubber tyres, like the metro in Paris. The entrance to the platforms is usually pretty oldfashoned and narrow and the platforms are only 52 m long, long enough for two units.
The Lille Métro operates from 5:00 until midnight, with trains every 1.5 - 4 minutes, every 6 - 8 minutes early morning and evenings. On Sundays there is a train every 4-6 minutes. Prices in Euro: Single E 1.15; 10 rides E 10.00; Day Pass E3.35; Week Pass E 11.00. All tickets are valid on buses, trams and métro. Special season tickets are available including TER regional trains and regional buses.
Something about the history: After trials were carried out by MATRA during the early 1970's, the CUDL decided in 1974 to build 4 VAL lines in the metropolitan area. Construction started in 1978 and the first line was inaugurated on 25 April 1983 between 4 Cantons and République. One year later, on 2 May 1984 the entire Line 1 opened (13.5 km long, 8.5 km underground). It links C.H.R. B Calmette in Lille to 4 Cantons in Villeneuve d'Ascq via Gare Lille Flandres (Central Station). All stations have doors between platform and train. Line 2 opened on 3 April 1989, initially called Ligne 1bis, between St. Philibert and Gares, later renamed Gare Lille Flandres (15.5 km, 7 km underground). In 1994, there was a one-station extension to the new TGV station Gare Lille Europe, and in 1995 the line reached Fort de Mons. On 18 Aug. 1999, Line 2 was extended to Tourcoing-Centre (12.5 km - 16 stations) and it reached C.H. Dron near the Belgian border on 27 Oct. 2000 (3.6 km). The entire Line 2 is now 32 km long with 43 stations (currently the longest automatic metro line in the world).
Metro trains in Lille are like rides at a theme park, they have no driver and you can sit right at the front at pretend you are a kid driving the train, a lot of fun. The trains are fast, especially because they are automated, and because of this there is less chance of them being affected by the dreaded French annual strike!
My friends and I enjoyed getting around them alot, what's more the access to the stations is good with many of them having escalators and lifts. It's a lot more modern, but smaller than the metro stations you will find in Paris. Make sure that you validate your ticket, so that you don't get caught out with the occasional spot checks by conductors.
Travel within Lille is also made easy, as there are a number of ways of getting around. The most popular method is the Metro. There are two metro lines in Lille linking many of the quartiers. The metro is also reasonably priced with a single journey costing 1,15 euros and a day ticket 3,35 euros.
The metro runs from 5.30 in the morning (6.30 on Sunday) until 12.30 at night.
Other travel options around Lille are by tram and bus and the tickets for these are the same as the Metro.